Someone else can chime in on what the exact legal terms are, but I'm pretty sure that it is against AA conditions of carriage to buy/redeem tickets that you do not have intention of using. That said, AA's enforcement mechanism for this rule--auto-cancellation of duplicate itineraries--only applies for duplicate itineraries that are physically impossible for the same person to fly, i.e. BOS-LAX one morning and another BOS-LAX that early afternoon. Your aunt's itineraries shouldn't fall under this umbrella based on your description.

I presume both tickets are being issued using miles from your account. As long as you are EXP at the time of the cancellation request, the miles will be redeposited for free.