The theory is that the hold is wiped when the transaction itself hits the account, and that's probably what happens most of the time. Or at least that's what we are told.

colmc's experience is disturbing, though. I'm not aware of having had this problem. However, when allowing a print of my credit card at hotel check-in and the like, it's the AmEx plat that is printed even if I use another card such as the AmEx BA at check-out. I just don't want too many holds to accumulate.