I've registered for a promo or two (on other airlines) that were targeted to others but not to me. Each time, I recognized that I was doing it at my own risk. Since I didn't really risk anything in any of these cases, there was no downside: either I'd get miles that I didn't really deserve, or I'd only get the miles I deserved.

I would never plan a trip on the assumption that I'd get miles from a targeted promo I wasn'teligible for. That seems foolhardy. Expecting US to honor promos just because someone was silly enough to do that isn't reasonable.

When you register for an AA promo, the confirming notice says that you also have to fulfill all the terms and conditions of the promo. If these terms and conditions include a restriction to people who received a targeted mailing, they're under no legal, moral or logical obligation to give anyone extra miles just because they found a code somewhere and keyed it in - any more than they're under an obligation to give someone a trans-Atlantic bonus if he/she registered for it and then flew from Chicago to Milwaukee. Knowing a code does not create eligibility for a promo.

The multiple-promo issue is separate. Unless there are rules to the contrary, anyone who registers for, qualifies for and earns miles under more than one promo ought to get them all. If US were to tell someone "we really didn't mean for you to get miles under more than one of these, even though you were eligible for all of them and we never said so," I for one would be royally p*ssed.