Board Thread:Questions and Answers/@comment-219.74.118.143-20140730161503/@comment-24956068-20140731143933

No, for that Power+ treasures, the effect does not stack.

But it is more like, you have more than one chance to get the prize. Imagine each treasure is a coin toss, when you have two treasures, you are doing the coin toss two times, giving you chances to get one (or even more, both) reward.