My character had the wizard clothes equipped as the cosmetic for the armor and an EPP equipped in the cosmetic of the back slot (I do that to be able to quick swap between EPP's).
The wardrobe picked my current set as it's configured set and allowed me to spawn extra copies of it, I believe it's intended for it to give the player any of the costumes ingame, but it also gave me an extra copy of the EPP which isn't even in the selection of possible cosmetics for the back slot.