As an aside to this conversation (like the open thread, btw) one of the things my neo-oldtyme ensemble does is research the melodies of traditional Appalachian fiddle tunes in search of the source songs. It's often tricky, because these melodies weren't necessarily written down longhand, and certainly not recorded until the last century. Well before publishing and copywriting were established, fiddlers/musicians just passed these tunes down to each other, often multi-generationally.
Even today here in Virginia, oldtyme music is VERY territorial... often when playing in unfamiliar company, we have to determine which region a particular tune came from so you know what/where the changes are. Seriously, it's commonplace to hear - Are you doing the Carroll County version or the Southern West Virginia version?
The jokes about it all sounds the same... yeah. It does if you don't know any better. =)