Client list shows duplicates after database migration


last year I lost all TeamSpeak data due to catastrophic hardware failure and my backups being on the same storage cluster which prompted me to investigate the migration from SQLite to my PostgreSQL db after recreating the server.
A while later I found the time to migrate and after restarting my server and connecting with YaTQA every db entry seemed to be duplicated. Since it worked flawlessly I ignored it and upgraded postgres-12 to postgres-14, which duplicated all entries again.
Last Sunday when I upgraded postgres-14 to postgres-15 every quadrupled entry was duplicated again.
The server still works, but it’s infuriating to look at the user database.

YaTQA server 1:
YaTQA server 2:

TeamSpeak 3 Client → List All Clients server 1:
List All Clients server 2:

I checked my database. Even tried to delete duplicate entries (there where none).
SELECT * FROM clients WHERE client_unique_id = 'ServerQuery';:

At this point it’s driving me insane.
Why do I see so many duplicate user entries in my TeamSpeak 3 Client?
How do I remove them?

Best regards