There is a Tixati setting in the following location:
Tixati Settings > Transfers > Meta-Info > "Save a .torrent file in this folder when a new transfer starts"
On my system I have this folder set to W:\Torrent Files

What I think the bug might be is that if I load a torrent into Tixati from the same folder (W:\Torrent Files) then Tixati will still create a (renamed) copy of the torrent file into the same folder when the torrent starts. There doesn't seem any point at all in doing this and it just makes the list of torrent files in that folder more difficult to read and work with. Don't copy or make duplicate torrent files when it isn't necessary to do so.

It also raises the question which of the (now) two torrent files is Tixati actually using as the active torrent that is associated to the download.

Hope this helps.