It happens all the time. The secret to being a genius is to not reveal your sources.

We are all influenced by those who came before us and sometimes that influence produces copies. I know that I have written a couple of tunes that turned out to be already written.

I do agree that the music corporations are bringing a lot of lawsuits to the courts. If it were up to the musicians I think a lot of those lawsuits would not have happened. Also based on a few previous videos some of these "plagiarism" lawsuits are on the verge of ridiculous.