Revert "Duplicate project name detection"

This reverts commits 404c6cf to ffb51fb and
commit a0a662c.

Fixes #12315

subprojects/composite-builds/src/integTest/groovy/org/gradle/integtests/composite/CompositeBuildDependencyGraphIntegrationTest.groovy

@@ -606,6 +606,33 @@ afterEvaluate {
         failure.assertHasCause("Module version 'org.test:b1:1.0' is not unique in composite: can be provided by [project :buildB:b1, project :buildC:b1].")
     }
 
+    def "reports failure to resolve dependencies when substitution is ambiguous within single participant"() {
+        given:
+        buildB
+        def buildC = multiProjectBuild("buildC", ['c1', 'c2']);
+        buildC.settingsFile << """
+            include ':nested:c1'
+"""
+        buildC.buildFile << """
+            allprojects {
+                apply plugin: 'java'
+            }
+"""
+        includedBuilds << buildC
+
+        buildA.buildFile << """
+            dependencies {
+                implementation "org.test:c1:1.0"
+            }
+"""
+
+        when:
+        checkDependenciesFails()
+
+        then:
+        failure.assertHasCause("Module version 'org.test:c1:1.0' is not unique in composite: can be provided by [project :buildC:c1, project :buildC:nested:c1].")
+    }
+
     def "reports failure to resolve dependencies when transitive dependency substitution is ambiguous"() {
         given:
         transitiveDependencyIsAmbiguous("'org.test:b1:2.0'")
@@ -720,22 +747,22 @@ afterEvaluate {
                 maven { url '$mavenRepo.uri' }
             }
 
-            configurations {
-                buildInputs
+            configurations { 
+                buildInputs 
                 create('default')
             }
-
+            
             dependencies {
                 buildInputs "org.test:test:1.2"
             }
-
+            
             task buildOutputs {
                 inputs.files configurations.buildInputs
                 doLast {
                     configurations.buildInputs.each { }
                 }
             }
-
+            
             artifacts {
                 "default" file: file("out.jar"), builtBy: buildOutputs
             }

subprojects/core/src/main/java/org/gradle/api/internal/artifacts/ProjectBackedModule.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2020 the original author or authors.
+ * Copyright 2012 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -13,13 +13,64 @@
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */
+
 package org.gradle.api.internal.artifacts;
 
 import org.gradle.api.Project;
 
-import java.util.List;
+public class ProjectBackedModule implements Module {
+
+    private final Project project;
+
+    public ProjectBackedModule(Project project) {
+        this.project = project;
+    }
+
+    @Override
+    public String getGroup() {
+        return project.getGroup().toString();
+    }
+
+    @Override
+    public String getName() {
+        return project.getName();
+    }
+
+    @Override
+    public String getVersion() {
+        return project.getVersion().toString();
+    }
+
+    @Override
+    public String getStatus() {
+        return project.getStatus().toString();
+    }
+
+    @Override
+    public String getProjectPath() {
+        return project.getPath();
+    }
+
+    @Override
+    public boolean equals(Object o) {
+        if (this == o) {
+            return true;
+        }
+        if (o == null || getClass() != o.getClass()) {
+            return false;
+        }
+
+        ProjectBackedModule that = (ProjectBackedModule) o;
+
+        if (project != null ? !project.equals(that.project) : that.project != null) {
+            return false;
+        }
+
+        return true;
+    }
 
-public interface ProjectBackedModule extends Module {
-    Project getProject();
-    List<Project> getProjectsWithSameCoordinates();
+    @Override
+    public int hashCode() {
+        return project != null ? project.hashCode() : 0;
+    }
 }

subprojects/core/src/main/java/org/gradle/internal/service/scopes/BuildScopeServices.java

@@ -26,10 +26,8 @@
 import org.gradle.api.internal.DocumentationRegistry;
 import org.gradle.api.internal.StartParameterInternal;
 import org.gradle.api.internal.artifacts.DefaultModule;
-import org.gradle.api.internal.artifacts.DefaultProjectModuleFactory;
 import org.gradle.api.internal.artifacts.DependencyManagementServices;
 import org.gradle.api.internal.artifacts.Module;
-import org.gradle.api.internal.artifacts.ProjectModuleFactory;
 import org.gradle.api.internal.artifacts.configurations.DependencyMetaDataProvider;
 import org.gradle.api.internal.classpath.ModuleRegistry;
 import org.gradle.api.internal.classpath.PluginModuleRegistry;
@@ -587,8 +585,4 @@ protected BuildScanUserInputHandler createBuildScanUserInputHandler(UserInputHan
     protected BuildInvocationDetails createBuildInvocationDetails(BuildStartedTime buildStartedTime) {
         return new DefaultBuildInvocationDetails(buildStartedTime);
     }
-
-    protected ProjectModuleFactory createProjectModuleIdentifierFactory(DefaultProjectRegistry<ProjectInternal> projectRegistry) {
-        return new DefaultProjectModuleFactory(projectRegistry);
-    }
 }