I had the same thought doing the quest, but really who says there can't be more than one type of puzzle box. The antiquity isn't the same type *shrug*.
I also thought, "Really? You spent your whole life looking for one? I have three at my house."
Hey, after the number of Morrowind players who turned the ruin upside down looking for that tiny box, ZOS took pity on ESO players and made it easier to see.