1. Deleting Tixati: I don't know where installed Tixati
stores its settings. Probably in AppData on Windows? However you can always run Tixati in portable mode then everything
of configuration and settings will be saved within that folder. That's useful for testing.
2. Duplicate transfer window: https://i.imgur.com/Q1yFSjW.png
is this what you see?
Clicking YES will add tracker URLs to the existing transfer and do nothing else.
Clicking NO will do nothing and will not add this torrent/magnet link.
If you came across two different torrent names and this message comes up then they're totally identical
Tixati tells you the transfer name too "debian-11.6.0-amd64-DVD-1.iso - TEST" as you named it inside Tixati. This means you go to TRANSFERS and search for the added torrent with that exact name.
If you are at a dead end then please take a screenshot of your Tixati when looking at Transfers
but make sure to censor all torrent names, trackers, IP addresses. This is a good rule on these forums.