I guess all the pros here probably have... but it was cool for me I wrote an instrumental tune about 15 yrs ago and recorded it. Recently a friend said, "I didn't realize that was a cover." I said it wasn't, I wrote it. He played a bit of a movie for me and sure enough, there was the tune as part of the soundtrack- same chords, melody, even same tempo and general instrumentation. I don't think there is any question of theft or anything. It's not like more than 10 people ever heard it as my recording. And after all, we're all using the same chords and notes as each other, there's gonna be overlap, right? I think the neatest thing was just a bit of validation- my tune was good enough to be in a movie. Cool! I honestly don't remember the movie, it was something about a funeral, but every time I try to remember it I get it mixed up with an episode of Bones. It'll come back to me tho.