[Skip]

I think Jeff is correct.
What may work is to identify the Bb instrument book tunes as such, and say that any tune not identified as being from the Bb book are C instrument tunes. I don't have any Bb instrument books available to check. Maybe you can make a separate folder for each type of book.
I'm not sure, but it seems to me that identical tunes in a particular key would be the same regardless of which book they were in, a key is only the name for a particular series of notes after all is said a done.