Originally Posted by
Often1
AA's software matches names, CC used, IP address, physical address and so forth. Duplicate or "impossible" bookings are cancelled. If you are lucky AA calls and asks which one. If you are unlucky, AA cancels the right one. If you are really, really unlucky, AA cancels both.
Ehh not completely true. There are many of us that have had a RT that went AAA-BBB-CCC-BBB-AAA and then end up buying a ticket BBB-DDD at the end or even CCC-DDD. I myself have done it way more than once.
If you did it at the same time which blatantly was to get around one-way rules (nesting tickets, etc), then AA will have a problem with it if you get caught.
I've 3 times had tickets involving LAX and bought another ticket on the same day to different destinations, had my number in and no problems whatsoever. Sure, I guess maybe I got lucky, but people's thoughts on AA's mysterious "duplicate booking" tool is grossly overinflated. If you booked it on the same routing the same day, yes it will be found. But it sure isnt looking at every single flight, every single passenger to verify they all have "legal" connections or routings.
ETA: I want to make it clear, YMMV, but I have done this due to plans changing. It was easier abandoning a ticket than trying to change for literally a thousand dollars.