[QUOTE=WeekendTraveler;35251934]
I don't think you can even buy another ticket (in any class of service) if you're already booked on the same flight with same AA number./QUOTE]
This is correct. The second ticket that you book will show as “on hold” and then will disappear.
Not sure about this point actually. I believe as long as the second reservation is ticketed, AA will not proactively cancel it. They might pursue you later for impossible / illogical booking, but I don't think there's an automated process for that. If you put the second reservation on hold, then it might get canceled before the deadline