diff --git a/lib/yarn-plugin-rsp-duplicates.js b/lib/yarn-plugin-rsp-duplicates.js
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+++ b/lib/yarn-plugin-rsp-duplicates.js
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+/*
+ * Copyright 2024 Adobe. All rights reserved.
+ * This file is licensed to you under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License. You may obtain a copy
+ * of the License at http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software distributed under
+ * the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR REPRESENTATIONS
+ * OF ANY KIND, either express or implied. See the License for the specific language
+ * governing permissions and limitations under the License.
+ */
+
+// This is a Yarn plugin to detect multiple installed versions of React Spectrum/React Aria packages.
+// It can be installed by running `yarn plugin import https://raw.githubusercontent.com/adobe/react-spectrum/main/lib/yarn-plugin-rsp-duplicates.js`.
+module.exports = {
+  name: 'plugin-rsp-duplicates',
+  factory: require => {
+    const {structUtils, MessageName, ReportError} = require('@yarnpkg/core');
+
+    return {
+      default: {
+        hooks: {
+          afterAllInstalled(project) {
+            let packages = new Map();
+            let hasRSP = false;
+            for (const pkg of project.storedPackages.values()) {
+              if (!structUtils.isVirtualLocator(pkg) && (pkg.scope === 'react-aria' || pkg.scope === 'react-spectrum' || pkg.scope === 'react-stately')) {
+                let key = `@${pkg.scope}/${pkg.name}`;
+                if (!packages.has(key)) {
+                  packages.set(key, new Set([pkg.version]));
+                } else {
+                  packages.get(key).add(pkg.version);
+                }
+                hasRSP ||= pkg.scope === 'react-spectrum';
+              }
+            }
+
+            let errors = [];
+            for (let [pkg, versions] of packages) {
+              if (versions.size > 1) {
+                errors.push(`    ${pkg}: ${[...versions].join(', ')}`);
+              }
+            }
+
+            if (errors.length) {
+              errors.sort();
+              throw new ReportError(
+                MessageName.EXCEPTION,
+                `Found multiple installed versions of ${hasRSP ? 'React Spectrum' : 'React Aria'} packages: \n\n`
+                  + errors.join('\n')
+                  + '\n\n You may be able to fix this by running `yarn dedupe`.'
+              );
+            }
+          }
+        }
+      }
+    };
+  }
+};