I don't have Lamma so I can't test it myself, and I don't remember seeing anything about it (but maybe I missed it):

What happens when you have the same enhancement in 2 trees? I know they don't stack in any way, but happens with their AP value: does it add to the total AP in both trees (would make sense imo)? or only in the one you took it first, basically forcing you to take more useless enhancements in the other tree to reach the next tier?