When playing the stage in freeplay I've accidentally come across a dupe glitch. Once you're at the 2nd snowman at the place you have to light the explosive to blow up the wall. I used a rocket launcher to blow up the wall, accidentally grabbed the torch, then built the snowman. I apparently lit the explosive when I moved as another explosive went off and the snowman was not built again, but the platform thing you also build was still there. I built the snowman again, and even though it still said 2/3 it gave me the treasure as the dupe confused the game. I then built the platform, and the one I originally built got replaced with this new one which made me realize what happened.

Don't know if this could be useful in a 100% run, but can be if that run is routed differently. I think to activate the glitch you blow the wall with a rocket launcher, then quickly grab a torch to lite the dynamite, then build the snowman. It will explode, then build it again.