diff --git a/packages/babel-parser/test/fixtures/flow/multiple-declarations/class/input.js b/packages/babel-parser/test/fixtures/flow/multiple-declarations/class/input.js
new file mode 100644
index 000000000000..fa5ff14cb9be
--- /dev/null
+++ b/packages/babel-parser/test/fixtures/flow/multiple-declarations/class/input.js
@@ -0,0 +1,2 @@
+declare class C1 {}
+class C1 {}
diff --git a/packages/babel-parser/test/fixtures/flow/multiple-declarations/class/options.json b/packages/babel-parser/test/fixtures/flow/multiple-declarations/class/options.json
new file mode 100644
index 000000000000..06ad6ded6032
--- /dev/null
+++ b/packages/babel-parser/test/fixtures/flow/multiple-declarations/class/options.json
@@ -0,0 +1,8 @@
+{
+  "sourceType": "module",
+  "plugins": [
+    "jsx",
+    "flow"
+  ],
+  "throws": "Identifier 'C1' has already been declared (2:6)"
+}
\ No newline at end of file
diff --git a/packages/babel-parser/test/fixtures/flow/multiple-declarations/declare-class/input.js b/packages/babel-parser/test/fixtures/flow/multiple-declarations/declare-class/input.js
new file mode 100644
index 000000000000..d9470b0fd596
--- /dev/null
+++ b/packages/babel-parser/test/fixtures/flow/multiple-declarations/declare-class/input.js
@@ -0,0 +1,6 @@
+declare class C1{}
+declare class C1{}
+
+declare module M1 {
+  declare class C1 {}
+}
diff --git a/packages/babel-parser/test/fixtures/flow/multiple-declarations/declare-class/output.json b/packages/babel-parser/test/fixtures/flow/multiple-declarations/declare-class/output.json
new file mode 100644
index 000000000000..149ca744eb22
--- /dev/null
+++ b/packages/babel-parser/test/fixtures/flow/multiple-declarations/declare-class/output.json
@@ -0,0 +1,253 @@
+{
+  "type": "File",
+  "start": 0,
+  "end": 82,
+  "loc": {
+    "start": {
+      "line": 1,
+      "column": 0
+    },
+    "end": {
+      "line": 6,
+      "column": 1
+    }
+  },
+  "program": {
+    "type": "Program",
+    "start": 0,
+    "end": 82,
+    "loc": {
+      "start": {
+        "line": 1,
+        "column": 0
+      },
+      "end": {
+        "line": 6,
+        "column": 1
+      }
+    },
+    "sourceType": "module",
+    "interpreter": null,
+    "body": [
+      {
+        "type": "DeclareClass",
+        "start": 0,
+        "end": 18,
+        "loc": {
+          "start": {
+            "line": 1,
+            "column": 0
+          },
+          "end": {
+            "line": 1,
+            "column": 18
+          }
+        },
+        "id": {
+          "type": "Identifier",
+          "start": 14,
+          "end": 16,
+          "loc": {
+            "start": {
+              "line": 1,
+              "column": 14
+            },
+            "end": {
+              "line": 1,
+              "column": 16
+            },
+            "identifierName": "C1"
+          },
+          "name": "C1"
+        },
+        "typeParameters": null,
+        "extends": [],
+        "implements": [],
+        "mixins": [],
+        "body": {
+          "type": "ObjectTypeAnnotation",
+          "start": 16,
+          "end": 18,
+          "loc": {
+            "start": {
+              "line": 1,
+              "column": 16
+            },
+            "end": {
+              "line": 1,
+              "column": 18
+            }
+          },
+          "callProperties": [],
+          "properties": [],
+          "indexers": [],
+          "internalSlots": [],
+          "exact": false
+        }
+      },
+      {
+        "type": "DeclareClass",
+        "start": 19,
+        "end": 37,
+        "loc": {
+          "start": {
+            "line": 2,
+            "column": 0
+          },
+          "end": {
+            "line": 2,
+            "column": 18
+          }
+        },
+        "id": {
+          "type": "Identifier",
+          "start": 33,
+          "end": 35,
+          "loc": {
+            "start": {
+              "line": 2,
+              "column": 14
+            },
+            "end": {
+              "line": 2,
+              "column": 16
+            },
+            "identifierName": "C1"
+          },
+          "name": "C1"
+        },
+        "typeParameters": null,
+        "extends": [],
+        "implements": [],
+        "mixins": [],
+        "body": {
+          "type": "ObjectTypeAnnotation",
+          "start": 35,
+          "end": 37,
+          "loc": {
+            "start": {
+              "line": 2,
+              "column": 16
+            },
+            "end": {
+              "line": 2,
+              "column": 18
+            }
+          },
+          "callProperties": [],
+          "properties": [],
+          "indexers": [],
+          "internalSlots": [],
+          "exact": false
+        }
+      },
+      {
+        "type": "DeclareModule",
+        "start": 39,
+        "end": 82,
+        "loc": {
+          "start": {
+            "line": 4,
+            "column": 0
+          },
+          "end": {
+            "line": 6,
+            "column": 1
+          }
+        },
+        "id": {
+          "type": "Identifier",
+          "start": 54,
+          "end": 56,
+          "loc": {
+            "start": {
+              "line": 4,
+              "column": 15
+            },
+            "end": {
+              "line": 4,
+              "column": 17
+            },
+            "identifierName": "M1"
+          },
+          "name": "M1"
+        },
+        "body": {
+          "type": "BlockStatement",
+          "start": 57,
+          "end": 82,
+          "loc": {
+            "start": {
+              "line": 4,
+              "column": 18
+            },
+            "end": {
+              "line": 6,
+              "column": 1
+            }
+          },
+          "body": [
+            {
+              "type": "DeclareClass",
+              "start": 61,
+              "end": 80,
+              "loc": {
+                "start": {
+                  "line": 5,
+                  "column": 2
+                },
+                "end": {
+                  "line": 5,
+                  "column": 21
+                }
+              },
+              "id": {
+                "type": "Identifier",
+                "start": 75,
+                "end": 77,
+                "loc": {
+                  "start": {
+                    "line": 5,
+                    "column": 16
+                  },
+                  "end": {
+                    "line": 5,
+                    "column": 18
+                  },
+                  "identifierName": "C1"
+                },
+                "name": "C1"
+              },
+              "typeParameters": null,
+              "extends": [],
+              "implements": [],
+              "mixins": [],
+              "body": {
+                "type": "ObjectTypeAnnotation",
+                "start": 78,
+                "end": 80,
+                "loc": {
+                  "start": {
+                    "line": 5,
+                    "column": 19
+                  },
+                  "end": {
+                    "line": 5,
+                    "column": 21
+                  }
+                },
+                "callProperties": [],
+                "properties": [],
+                "indexers": [],
+                "internalSlots": [],
+                "exact": false
+              }
+            }
+          ]
+        },
+        "kind": "CommonJS"
+      }
+    ],
+    "directives": []
+  }
+}
\ No newline at end of file
diff --git a/packages/babel-parser/test/fixtures/flow/multiple-declarations/declare-function/input.js b/packages/babel-parser/test/fixtures/flow/multiple-declarations/declare-function/input.js
new file mode 100644
index 000000000000..fb98eb970189
--- /dev/null
+++ b/packages/babel-parser/test/fixtures/flow/multiple-declarations/declare-function/input.js
@@ -0,0 +1,3 @@
+declare function F1(): void
+declare function F1(): void
+function F1() {}
diff --git a/packages/babel-parser/test/fixtures/flow/multiple-declarations/declare-function/output.json b/packages/babel-parser/test/fixtures/flow/multiple-declarations/declare-function/output.json
new file mode 100644
index 000000000000..ad507ae14079
--- /dev/null
+++ b/packages/babel-parser/test/fixtures/flow/multiple-declarations/declare-function/output.json
@@ -0,0 +1,249 @@
+{
+  "type": "File",
+  "start": 0,
+  "end": 72,
+  "loc": {
+    "start": {
+      "line": 1,
+      "column": 0
+    },
+    "end": {
+      "line": 3,
+      "column": 16
+    }
+  },
+  "program": {
+    "type": "Program",
+    "start": 0,
+    "end": 72,
+    "loc": {
+      "start": {
+        "line": 1,
+        "column": 0
+      },
+      "end": {
+        "line": 3,
+        "column": 16
+      }
+    },
+    "sourceType": "module",
+    "interpreter": null,
+    "body": [
+      {
+        "type": "DeclareFunction",
+        "start": 0,
+        "end": 27,
+        "loc": {
+          "start": {
+            "line": 1,
+            "column": 0
+          },
+          "end": {
+            "line": 1,
+            "column": 27
+          }
+        },
+        "id": {
+          "type": "Identifier",
+          "start": 17,
+          "end": 27,
+          "loc": {
+            "start": {
+              "line": 1,
+              "column": 17
+            },
+            "end": {
+              "line": 1,
+              "column": 27
+            },
+            "identifierName": "F1"
+          },
+          "name": "F1",
+          "typeAnnotation": {
+            "type": "TypeAnnotation",
+            "start": 19,
+            "end": 27,
+            "loc": {
+              "start": {
+                "line": 1,
+                "column": 19
+              },
+              "end": {
+                "line": 1,
+                "column": 27
+              }
+            },
+            "typeAnnotation": {
+              "type": "FunctionTypeAnnotation",
+              "start": 19,
+              "end": 27,
+              "loc": {
+                "start": {
+                  "line": 1,
+                  "column": 19
+                },
+                "end": {
+                  "line": 1,
+                  "column": 27
+                }
+              },
+              "typeParameters": null,
+              "params": [],
+              "rest": null,
+              "returnType": {
+                "type": "VoidTypeAnnotation",
+                "start": 23,
+                "end": 27,
+                "loc": {
+                  "start": {
+                    "line": 1,
+                    "column": 23
+                  },
+                  "end": {
+                    "line": 1,
+                    "column": 27
+                  }
+                }
+              }
+            }
+          }
+        },
+        "predicate": null
+      },
+      {
+        "type": "DeclareFunction",
+        "start": 28,
+        "end": 55,
+        "loc": {
+          "start": {
+            "line": 2,
+            "column": 0
+          },
+          "end": {
+            "line": 2,
+            "column": 27
+          }
+        },
+        "id": {
+          "type": "Identifier",
+          "start": 45,
+          "end": 55,
+          "loc": {
+            "start": {
+              "line": 2,
+              "column": 17
+            },
+            "end": {
+              "line": 2,
+              "column": 27
+            },
+            "identifierName": "F1"
+          },
+          "name": "F1",
+          "typeAnnotation": {
+            "type": "TypeAnnotation",
+            "start": 47,
+            "end": 55,
+            "loc": {
+              "start": {
+                "line": 2,
+                "column": 19
+              },
+              "end": {
+                "line": 2,
+                "column": 27
+              }
+            },
+            "typeAnnotation": {
+              "type": "FunctionTypeAnnotation",
+              "start": 47,
+              "end": 55,
+              "loc": {
+                "start": {
+                  "line": 2,
+                  "column": 19
+                },
+                "end": {
+                  "line": 2,
+                  "column": 27
+                }
+              },
+              "typeParameters": null,
+              "params": [],
+              "rest": null,
+              "returnType": {
+                "type": "VoidTypeAnnotation",
+                "start": 51,
+                "end": 55,
+                "loc": {
+                  "start": {
+                    "line": 2,
+                    "column": 23
+                  },
+                  "end": {
+                    "line": 2,
+                    "column": 27
+                  }
+                }
+              }
+            }
+          }
+        },
+        "predicate": null
+      },
+      {
+        "type": "FunctionDeclaration",
+        "start": 56,
+        "end": 72,
+        "loc": {
+          "start": {
+            "line": 3,
+            "column": 0
+          },
+          "end": {
+            "line": 3,
+            "column": 16
+          }
+        },
+        "id": {
+          "type": "Identifier",
+          "start": 65,
+          "end": 67,
+          "loc": {
+            "start": {
+              "line": 3,
+              "column": 9
+            },
+            "end": {
+              "line": 3,
+              "column": 11
+            },
+            "identifierName": "F1"
+          },
+          "name": "F1"
+        },
+        "generator": false,
+        "async": false,
+        "params": [],
+        "body": {
+          "type": "BlockStatement",
+          "start": 70,
+          "end": 72,
+          "loc": {
+            "start": {
+              "line": 3,
+              "column": 14
+            },
+            "end": {
+              "line": 3,
+              "column": 16
+            }
+          },
+          "body": [],
+          "directives": []
+        }
+      }
+    ],
+    "directives": []
+  }
+}
\ No newline at end of file
diff --git a/packages/babel-parser/test/fixtures/flow/multiple-declarations/declare-var/input.js b/packages/babel-parser/test/fixtures/flow/multiple-declarations/declare-var/input.js
new file mode 100644
index 000000000000..21b4f11b204c
--- /dev/null
+++ b/packages/babel-parser/test/fixtures/flow/multiple-declarations/declare-var/input.js
@@ -0,0 +1,3 @@
+declare var V1;
+declare var V1;
+var V1;
diff --git a/packages/babel-parser/test/fixtures/flow/multiple-declarations/declare-var/output.json b/packages/babel-parser/test/fixtures/flow/multiple-declarations/declare-var/output.json
new file mode 100644
index 000000000000..b96badb7fe54
--- /dev/null
+++ b/packages/babel-parser/test/fixtures/flow/multiple-declarations/declare-var/output.json
@@ -0,0 +1,150 @@
+{
+  "type": "File",
+  "start": 0,
+  "end": 39,
+  "loc": {
+    "start": {
+      "line": 1,
+      "column": 0
+    },
+    "end": {
+      "line": 3,
+      "column": 7
+    }
+  },
+  "program": {
+    "type": "Program",
+    "start": 0,
+    "end": 39,
+    "loc": {
+      "start": {
+        "line": 1,
+        "column": 0
+      },
+      "end": {
+        "line": 3,
+        "column": 7
+      }
+    },
+    "sourceType": "module",
+    "interpreter": null,
+    "body": [
+      {
+        "type": "DeclareVariable",
+        "start": 0,
+        "end": 15,
+        "loc": {
+          "start": {
+            "line": 1,
+            "column": 0
+          },
+          "end": {
+            "line": 1,
+            "column": 15
+          }
+        },
+        "id": {
+          "type": "Identifier",
+          "start": 12,
+          "end": 14,
+          "loc": {
+            "start": {
+              "line": 1,
+              "column": 12
+            },
+            "end": {
+              "line": 1,
+              "column": 14
+            },
+            "identifierName": "V1"
+          },
+          "name": "V1"
+        }
+      },
+      {
+        "type": "DeclareVariable",
+        "start": 16,
+        "end": 31,
+        "loc": {
+          "start": {
+            "line": 2,
+            "column": 0
+          },
+          "end": {
+            "line": 2,
+            "column": 15
+          }
+        },
+        "id": {
+          "type": "Identifier",
+          "start": 28,
+          "end": 30,
+          "loc": {
+            "start": {
+              "line": 2,
+              "column": 12
+            },
+            "end": {
+              "line": 2,
+              "column": 14
+            },
+            "identifierName": "V1"
+          },
+          "name": "V1"
+        }
+      },
+      {
+        "type": "VariableDeclaration",
+        "start": 32,
+        "end": 39,
+        "loc": {
+          "start": {
+            "line": 3,
+            "column": 0
+          },
+          "end": {
+            "line": 3,
+            "column": 7
+          }
+        },
+        "declarations": [
+          {
+            "type": "VariableDeclarator",
+            "start": 36,
+            "end": 38,
+            "loc": {
+              "start": {
+                "line": 3,
+                "column": 4
+              },
+              "end": {
+                "line": 3,
+                "column": 6
+              }
+            },
+            "id": {
+              "type": "Identifier",
+              "start": 36,
+              "end": 38,
+              "loc": {
+                "start": {
+                  "line": 3,
+                  "column": 4
+                },
+                "end": {
+                  "line": 3,
+                  "column": 6
+                },
+                "identifierName": "V1"
+              },
+              "name": "V1"
+            },
+            "init": null
+          }
+        ],
+        "kind": "var"
+      }
+    ],
+    "directives": []
+  }
+}
\ No newline at end of file
diff --git a/packages/babel-parser/test/fixtures/flow/multiple-declarations/interface/input.js b/packages/babel-parser/test/fixtures/flow/multiple-declarations/interface/input.js
new file mode 100644
index 000000000000..bca93948ce50
--- /dev/null
+++ b/packages/babel-parser/test/fixtures/flow/multiple-declarations/interface/input.js
@@ -0,0 +1,2 @@
+interface I {};
+interface I {};
diff --git a/packages/babel-parser/test/fixtures/flow/multiple-declarations/interface/options.json b/packages/babel-parser/test/fixtures/flow/multiple-declarations/interface/options.json
new file mode 100644
index 000000000000..5672ce1b6444
--- /dev/null
+++ b/packages/babel-parser/test/fixtures/flow/multiple-declarations/interface/options.json
@@ -0,0 +1,8 @@
+{
+  "sourceType": "module",
+  "plugins": [
+    "jsx",
+    "flow"
+  ],
+  "throws": "Identifier 'I' has already been declared (2:10)"
+}
\ No newline at end of file
diff --git a/packages/babel-parser/test/fixtures/flow/multiple-declarations/type/input.js b/packages/babel-parser/test/fixtures/flow/multiple-declarations/type/input.js
new file mode 100644
index 000000000000..273aa1c7176c
--- /dev/null
+++ b/packages/babel-parser/test/fixtures/flow/multiple-declarations/type/input.js
@@ -0,0 +1,2 @@
+type T1 = string;
+type T1 = number;
diff --git a/packages/babel-parser/test/fixtures/flow/multiple-declarations/type/options.json b/packages/babel-parser/test/fixtures/flow/multiple-declarations/type/options.json
new file mode 100644
index 000000000000..946261f4e872
--- /dev/null
+++ b/packages/babel-parser/test/fixtures/flow/multiple-declarations/type/options.json
@@ -0,0 +1,8 @@
+{
+  "sourceType": "module",
+  "plugins": [
+    "jsx",
+    "flow"
+  ],
+  "throws": "Identifier 'T1' has already been declared (2:5)"
+}
\ No newline at end of file