Advanced Race Guide: page 72
Dual Talent: Some humans are uniquely skilled at maximizing their natural gifts. These humans pick two ability scores and gain a +2 racial bonus in each of those scores. This racial trait replaces the +2 bonus to any one ability score, the bonus feat, and the skilled traits.
So you could have it with the Adopted trait.
Adopted: You were adopted and raised by someone not of your actual race, and raised in a society not your own. As a result, you picked up a race trait from your adoptive parents and society, and may immediately select a race trait from your adoptive parents' race.
BUT, would it stack with the receiving race's bonus' to ability scores?
Yes.. after thinking about it... the receiving race doesnt have the bonus feat, and the skilled traits. anyway... So they can't be 'replaced'.
Yeah, you arrived at the right conclusion, but you got there via the wrong means.
You cannot use Adopted to take the Dual Talent alternate racial trait, but the problem isn't that they don't have the needed racial traits to trade out.
The problem is that a racial trait is not the same thing as a race trait. A race trait is a trait, of the race category. It is a separate rules element than racial traits.