Do multiple effects of the same power stack

Question

During the last session, we had two PC's with the same power: a full Bard and a Bard/Warlord Hybrid both had the daily power Stirring Shout.

Stirring Shout has an effect:

Effect: Until end of encounter, whenever an ally hits the target, he regains CHA HP

Do these two effect stack? Or is only the highest CHA modifier applied?

(And as a side question; is it acceptable to rule the effects stack, as this is an effect from a daily power?)

Answer 1

This isn't a case of two powers giving a bonus to a single roll or defence. There isn't any actual stacking here, in effect, they go off sequentially and just have identical benefits. They both apply.