Consider a power like the Legacy's "Galvanize":

Until the start of your next turn, increase damage dealt by hero targets by 1.

How does this interact with powers that deal two different types of damage, such as Fanatic's "Exorcism":

Fanatic deals 1 target 1 melee damage and 1 radiant damage.

Does Fanatic deal 2 melee damage and 2 radiant damage? Or 2 of one type and 1 of another type of the player's choice?