This kid at my school claims that he took all 8 AAMC practice tests and one of the exact same passages ended up on his real test. Does this ever actually happen or was he extremely lucky?
There was one on mine's as well that if not verbatim was extremely close to a question on a practice mcat (can't remember).
But I'm fairly certain that this was a weird occurrence and that the odds of it happening again are low- so OP, i wouldn't expect it to occur on your MCAT, or at least not to an appreciable extent.
I don't know if they do from the AAMC FL, but last year I had a bio passage on blood clotting and the giant flow diagram they presented was the exact same one as I had on a Kaplan FL. Weird.