diff --git a/CHANGELOG.md b/CHANGELOG.md
index cdc5370e3d7..4b8dd409d12 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -4,7 +4,7 @@
 <!-- CHANGELOG NEWEST -->
 
 - FIX findByIds not working with modify and patch [#6592](https://github.com/pubkey/rxdb/pull/6592)
-
+- FIX bulk inserting 2 docs with same primary key should throw [#6589](https://github.com/pubkey/rxdb/pull/6589)
 <!-- ADD new changes here! -->
 
 <!-- /CHANGELOG NEWEST -->
diff --git a/src/plugins/dev-mode/error-messages.ts b/src/plugins/dev-mode/error-messages.ts
index 41cefc99429..4b705b3eeb1 100644
--- a/src/plugins/dev-mode/error-messages.ts
+++ b/src/plugins/dev-mode/error-messages.ts
@@ -100,6 +100,7 @@ export const ERROR_MESSAGES = {
     COL20: 'Storage write error',
     COL21: 'The RxCollection is destroyed or removed already, either from this JavaScript realm or from another, like a browser tab',
     CONFLICT: 'Document update conflict. When changing a document you must work on the previous revision',
+    COL22: '.bulkInsert() and .bulkUpsert() cannot be run with multiple documents that have the same primary key',
 
     // rx-document.js
     DOC1: 'RxDocument.get$ cannot get observable of in-array fields because order cannot be guessed',
diff --git a/src/rx-collection.ts b/src/rx-collection.ts
index 8043116f67a..38bd326e14c 100644
--- a/src/rx-collection.ts
+++ b/src/rx-collection.ts
@@ -376,6 +376,7 @@ export class RxCollectionBase<
 
         const primaryPath = this.schema.primaryPath;
 
+        const ids = new Set<string>();
 
         /**
          * This code is a bit redundant for better performance.
@@ -386,6 +387,7 @@ export class RxCollectionBase<
         if (this.hasHooks('pre', 'insert')) {
             insertRows = await Promise.all(
                 docsData.map(docData => {
+                    ids.add((docData as any)[primaryPath]);
                     const useDocData = fillObjectDataBeforeInsert(this.schema, docData);
                     return this._runHooks('pre', 'insert', useDocData)
                         .then(() => {
@@ -398,11 +400,22 @@ export class RxCollectionBase<
             const schema = this.schema;
             for (let index = 0; index < docsData.length; index++) {
                 const docData = docsData[index];
+                ids.add((docData as any)[primaryPath]);
                 const useDocData = fillObjectDataBeforeInsert(schema, docData);
                 insertRows[index] = { document: useDocData };
             }
         }
 
+
+        if (ids.size !== docsData.length) {
+            throw newRxError('COL22', {
+                collection: this.name,
+                args: {
+                    documents: docsData
+                }
+            });
+        }
+
         const results = await this.storageInstance.bulkWrite(
             insertRows,
             'rx-collection-bulk-insert'
diff --git a/test/unit/rx-collection.test.ts b/test/unit/rx-collection.test.ts
index 0eec38dafeb..974e18387d9 100644
--- a/test/unit/rx-collection.test.ts
+++ b/test/unit/rx-collection.test.ts
@@ -389,6 +389,29 @@ describe('rx-collection.test.ts', () => {
                     assert.strictEqual(ret.error.length, 1);
                     db.destroy();
                 });
+                /**
+                 * @link https://github.com/pubkey/rxdb/pull/6589
+                 */
+                it('should throw on duplicate ids', async () => {
+                    const db = await createRxDatabase({
+                        name: randomCouchString(10),
+                        storage: config.storage.getStorage(),
+                    });
+                    const collections = await db.addCollections({
+                        human: { schema: schemas.primaryHuman }
+                    });
+
+                    const human1 = schemaObjects.humanData('same-id');
+                    const human2 = schemaObjects.humanData('same-id');
+
+                    await assertThrows(
+                        () => collections.human.bulkInsert([human1, human2]),
+                        'RxError',
+                        'COL22'
+                    );
+
+                    db.destroy();
+                });
             });
         });
         describe('.find()', () => {
@@ -1528,6 +1551,39 @@ describe('rx-collection.test.ts', () => {
 
                 c.database.destroy();
             });
+            /**
+             * @link https://github.com/pubkey/rxdb/pull/6589
+             */
+            it('should throw on duplicate ids', async () => {
+                const db = await createRxDatabase({
+                    name: randomCouchString(10),
+                    storage: config.storage.getStorage(),
+                });
+                const collections = await db.addCollections({
+                    human: { schema: schemas.primaryHuman }
+                });
+
+                const human1 = schemaObjects.humanData('same-id');
+                const human2 = schemaObjects.humanData('same-id');
+
+                await assertThrows(
+                    () => collections.human.bulkUpsert([human1, human2]),
+                    'RxError',
+                    'COL22'
+                );
+
+                // should be the same behavior even if the document already exists
+                await collections.human.insert(human1);
+                await assertThrows(
+                    () => collections.human.bulkUpsert([human1, human2]),
+                    'RxError',
+                    'COL22'
+                );
+
+
+
+                db.destroy();
+            });
         });
         describeParallel('.upsert()', () => {
             describe('positive', () => {