Zaruthustran
The tingling means it’s working!
It's still two chances of getting Quarry damage in, and you still add magic bonuses and the like to each arrow. But there are plenty of other threads about Twin Strike, I think.
Just to clarify, it's two chances to add Quarry damage ONCE. You only get to add quarry damage 1/round.
So even if both attacks hit, you only add quarry damage to one of the attacks.