diff --git a/CONTRIBUTING.md b/CONTRIBUTING.md
index a3c40c5851..1f466461cd 100644
--- a/CONTRIBUTING.md
+++ b/CONTRIBUTING.md
@@ -229,7 +229,7 @@ Before pushing your code changes make sure there are no linting errors with `npm
 
 ### Tests
 
-Running the integration test requires you to install [Docker](https://docs.docker.com/engine/installation) on your machine.
+Running the integration test requires you to install [Docker](https://docs.docker.com/engine/installation) on your machine. Note: the tests assume that running `git init` will create a `master` branch by default. If your local `git` is configured differently (see [`init.defaultBranch`](https://github.blog/2020-07-27-highlights-from-git-2-28/#introducing-init-defaultbranch)), change it temporarily when running the tests.
 
 All the [semantic-release](https://github.com/semantic-release) repositories use [AVA](https://github.com/avajs/ava) for writing and running tests.
 
diff --git a/lib/definitions/errors.js b/lib/definitions/errors.js
index a602983803..b125b778d8 100644
--- a/lib/definitions/errors.js
+++ b/lib/definitions/errors.js
@@ -29,6 +29,10 @@ Please make sure to add the \`repositoryUrl\` to the [semantic-release configura
       'docs/usage/configuration.md'
     )}).`,
   }),
+  EDUPLICATEREPOSITORYKEY: ({packageJsonPath}) => ({
+    message: 'Duplicate `"repository"` key in package.json.',
+    details: `Your package.json file at ${packageJsonPath} has more than one "repository" keys.`,
+  }),
   EGITNOPERMISSION: ({options: {repositoryUrl}, branch: {name}}) => ({
     message: 'Cannot push to the Git repository.',
     details: `**semantic-release** cannot push the version tag to the branch \`${name}\` on the remote Git repository with URL \`${repositoryUrl}\`.
diff --git a/lib/get-config.js b/lib/get-config.js
index bd40cecc1d..e7bf683284 100644
--- a/lib/get-config.js
+++ b/lib/get-config.js
@@ -1,12 +1,15 @@
+const {readFile} = require('fs').promises;
 const {castArray, pickBy, isNil, isString, isPlainObject} = require('lodash');
-const readPkgUp = require('read-pkg-up');
+const findPkgUp = require('pkg-up');
 const {cosmiconfig} = require('cosmiconfig');
 const resolveFrom = require('resolve-from');
+const findDuplicatedPropertyKeys = require('find-duplicated-property-keys');
 const debug = require('debug')('semantic-release:config');
 const {repoUrl} = require('./git');
 const PLUGINS_DEFINITIONS = require('./definitions/plugins');
 const plugins = require('./plugins');
 const {validatePlugin, parseConfig} = require('./plugins/utils');
+const getError = require('./get-error');
 
 const CONFIG_NAME = 'release';
 const CONFIG_FILES = [
@@ -74,7 +77,7 @@ module.exports = async (context, cliOptions) => {
       {name: 'beta', prerelease: true},
       {name: 'alpha', prerelease: true},
     ],
-    repositoryUrl: (await pkgRepoUrl({normalize: false, cwd})) || (await repoUrl({cwd, env})),
+    repositoryUrl: (await pkgRepoUrl({cwd})) || (await repoUrl({cwd, env})),
     tagFormat: `v\${version}`,
     plugins: [
       '@semantic-release/commit-analyzer',
@@ -93,6 +96,18 @@ module.exports = async (context, cliOptions) => {
 };
 
 async function pkgRepoUrl(options) {
-  const {packageJson} = (await readPkgUp(options)) || {};
-  return packageJson && (isPlainObject(packageJson.repository) ? packageJson.repository.url : packageJson.repository);
+  const packageJsonPath = await findPkgUp(options);
+  if (!packageJsonPath) return;
+
+  const packageJsonString = await readFile(packageJsonPath, 'utf-8');
+  const result = findDuplicatedPropertyKeys(packageJsonString);
+
+  if (result.length > 0) {
+    throw getError('EDUPLICATEREPOSITORYKEY', {packageJsonPath});
+  }
+
+  const {repository} = require(packageJsonPath);
+  if (!repository) return;
+
+  return isPlainObject(repository) ? repository.url : repository;
 }
diff --git a/package.json b/package.json
index fdbf3b90f0..12146b8893 100644
--- a/package.json
+++ b/package.json
@@ -31,6 +31,7 @@
     "env-ci": "^5.0.0",
     "execa": "^4.0.0",
     "figures": "^3.0.0",
+    "find-duplicated-property-keys": "^1.2.2",
     "find-versions": "^3.0.0",
     "get-stream": "^5.0.0",
     "git-log-parser": "^1.2.0",
@@ -42,7 +43,7 @@
     "micromatch": "^4.0.2",
     "p-each-series": "^2.1.0",
     "p-reduce": "^2.0.0",
-    "read-pkg-up": "^7.0.0",
+    "pkg-up": "^3.1.0",
     "resolve-from": "^5.0.0",
     "semver": "^7.3.2",
     "semver-diff": "^3.1.1",
@@ -128,7 +129,8 @@
     "prettier": true,
     "space": true,
     "rules": {
-      "unicorn/string-content": "off"
+      "unicorn/string-content": "off",
+      "node/no-unsupported-features/node-builtins": "off"
     }
   }
 }
diff --git a/test/get-config.test.js b/test/get-config.test.js
index 4e5b456708..f44a90b9d0 100644
--- a/test/get-config.test.js
+++ b/test/get-config.test.js
@@ -516,3 +516,21 @@ test('Throw an Error if one of the shareable config cannot be found', async (t)
     code: 'MODULE_NOT_FOUND',
   });
 });
+
+test('Throw an Error if package.json has duplicate "repository" key', async (t) => {
+  // Create a git repository, set the current working directory at the root of the repo
+  const {cwd} = await gitRepo();
+
+  // Create package.json with duplicate "repository" key
+  await writeFile(
+    path.resolve(cwd, 'package.json'),
+    `{
+    "repository": "https://github.com/octocat/repository",
+    "repository": "https://github.com/octocat/repository"
+  }`
+  );
+
+  const error = await t.throwsAsync(t.context.getConfig({cwd}));
+  t.is(error.code, 'EDUPLICATEREPOSITORYKEY');
+  t.is(error.message, 'Duplicate `"repository"` key in package.json.');
+});