Duplicate messages in replicated HA topology when backup is shutdowned

Scenario

1. Configure 2 nodes in replicated dedicated topology
2. Start live (node-1) and backup (node-2)
3. Start producer
4. Shut down node-2
5. Stop producer
6. Check if there are some duplicates on node-1 using CLI operation list-messages

Expectation: there is no duplications

Actual state: there are 10 messages with the same _AMQ_DUPL_ID twice

After that Backup is shut downed, the Live is not able to replicate its data to Backup. It waits 30 seconds until timeouts expire. Meanwhile producer does not get response from Live and it gets TimeoutException on commit. It retries to send the same batch of messages and then commit them again. I think that problem is at this point. The Live does not detect duplicate messages.