Hidden Power says:
You gain a bonus to the damage rolls of your vampire powers and vampire paragon path powers. The bonus equals your Charisma modifier.
So, let's say you're a level one vampire. You use Taste of Life, dealing 1d8+ dex. You also trigger your encounter, blood drinker, which triggers when you use a vampire melee at-will and does 1d10 extra damage (and gives a healing surge but that doesn't matter for this).
So, my question is, would Hidden Power trigger both for Taste of Life and for Blood Drinker, thus doing 2Cha mod extra dmg.
As a drow taking standard array (18 Cha, 16 Dex) that could mean 29 damage max, and 13 min, which I guess makes sense because of the big vampire drawbacks.
I'm perfectly fine with just houseruling it but if there's been some ruling on it I would prefer that.