Data loss is painful, especially with unique events like you described. Sorry.
I think you'd be better served by creating a
Template to start your sessions from so please check this out. Also, using
Remove instead of Delete is a safer option (though might require more cleanup later).
Curious though, since you said that you duplicated the folders... that should have resulted in 2 copies of all files (at least the first time). Do any of your session folders (Audio Files) contain these 'lost' files?
update: Just tested this and if I dupe a session's folder then delete an audio file from a session it doesn't delete both audio files - deleting an audio file from the session in my copied folder killed the audio file from that duped folder, not from the original