diff --git a/queue_job/jobrunner/channels.py b/queue_job/jobrunner/channels.py
index c895d9caf..028409c67 100644
--- a/queue_job/jobrunner/channels.py
+++ b/queue_job/jobrunner/channels.py
@@ -799,6 +799,62 @@ class ChannelManager:
     >>> cm.notify(db, 'S', 'S3', 3, 0, 10, None, 'done')
     >>> pp(list(cm.get_jobs_to_run(now=105)))
     []
+
+    Test handling of duplicate job UUIDs across different databases.
+    This can happen when a database is duplicated/cloned and both databases
+    notify the same job runner with the same job UUID.
+
+    >>> cm = ChannelManager()
+    >>> cm.simple_configure('root:4,D:2')
+
+    Create a job in db1
+
+    >>> cm.notify('db1', 'D', 'dup-uuid-1', 1, 0, 10, None, 'pending')
+    >>> job = cm._jobs_by_uuid.get('dup-uuid-1')
+    >>> job.db_name
+    'db1'
+    >>> len(cm._jobs_by_uuid)
+    1
+
+    Same UUID notified from a different database (db2) - simulates cloned DB.
+    The job should be recreated for the new database.
+
+    >>> cm.notify('db2', 'D', 'dup-uuid-1', 1, 0, 10, None, 'pending')
+    >>> job = cm._jobs_by_uuid.get('dup-uuid-1')
+    >>> job.db_name
+    'db2'
+    >>> len(cm._jobs_by_uuid)
+    1
+
+    Verify job can be run from the new database
+
+    >>> pp(list(cm.get_jobs_to_run(now=100)))
+    [<ChannelJob dup-uuid-1>]
+
+    Test multiple database switches for the same UUID
+
+    >>> cm.notify('db3', 'D', 'dup-uuid-1', 1, 0, 10, None, 'pending')
+    >>> job = cm._jobs_by_uuid.get('dup-uuid-1')
+    >>> job.db_name
+    'db3'
+
+    Create another job with different UUID in db1 and verify it coexists
+
+    >>> cm.notify('db1', 'D', 'other-uuid', 2, 0, 10, None, 'pending')
+    >>> len(cm._jobs_by_uuid)
+    2
+    >>> cm._jobs_by_uuid.get('dup-uuid-1').db_name
+    'db3'
+    >>> cm._jobs_by_uuid.get('other-uuid').db_name
+    'db1'
+
+    Both jobs should be available to run
+
+    >>> jobs = list(cm.get_jobs_to_run(now=100))
+    >>> len(jobs)
+    2
+    >>> sorted([j.uuid for j in jobs])
+    ['dup-uuid-1', 'other-uuid']
     """
 
     def __init__(self):
@@ -1029,22 +1085,31 @@ def notify(
         channel = self.get_channel_by_name(channel_name, parent_fallback=True)
         job = self._jobs_by_uuid.get(uuid)
         if job:
-            # db_name is invariant
-            assert job.db_name == db_name
-            # date_created is invariant
-            assert job.date_created == date_created
-            # if one of the job properties that influence
-            # scheduling order has changed, we remove the job
-            # from the queues and create a new job object
-            if (
-                seq != job.seq
-                or priority != job.priority
-                or eta != job.eta
-                or channel != job.channel
-            ):
-                _logger.debug("job %s properties changed, rescheduling it", uuid)
+            # if db_name differs, this is likely a cloned database
+            if job.db_name != db_name:
+                _logger.warning(
+                    "job %s exists in multiple databases (%s and %s). recreating it",
+                    uuid,
+                    job.db_name,
+                    db_name,
+                )
                 self.remove_job(uuid)
                 job = None
+            else:
+                # date_created is invariant
+                assert job.date_created == date_created
+                # if one of the job properties that influence
+                # scheduling order has changed, we remove the job
+                # from the queues and create a new job object
+                if (
+                    seq != job.seq
+                    or priority != job.priority
+                    or eta != job.eta
+                    or channel != job.channel
+                ):
+                    _logger.debug("job %s properties changed, rescheduling it", uuid)
+                    self.remove_job(uuid)
+                    job = None
         if not job:
             job = ChannelJob(db_name, channel, uuid, seq, date_created, priority, eta)
             self._jobs_by_uuid[uuid] = job