double weakness

Okay a fellow professor and I got into an arguement about applying double weaknesses. If a kecleon with both grass and psychic energy does damage to a gardevoir ex, does the attack do double or quadruple damage. I think it only does double damage, because the game only checks for any weakness at all, and doubles it. It shouldn't double for each weakness.

 

Q. If Kecleon has two different colored basic energies attached, and it attacks a Pokemon with weakness to both of those colors (i.e. Kabutops-EX), is the weakness calculation doubled because Kecleon is both types?
A. Sure. Damage would be up to x4 for the appropriate double Weakness. (Sep 11, 2003 PUI Rules Team Meeting)