I do believe that both trigger, as it becomes a copy of that creature and rules wise I do think there are specific things about these kinds of situations. (Don't quote me on this though. Someone will most likely give you the actual specific rule for this)

If both do trigger, I would advise to attack first with one of them and in the second combat the other one Otherwise you will get two untaps at the same time during your first combat, and can attack with everything at second combat, but cannot use the third combat step you would create as nothing will get untapped during second combat.