It depends upon your personal preferences. An oven glove typically comes as a single piece, but you can also find a double set in the market for holding hot pots by both hands. It is for sure safer to hold something by two hands rather than one. If you are baking like a half-pound cake, one mitt is enough to pick it, whereas, for a 2 pounds dish, you might require both your hands and hence, two mitts. So, go for two mitts if you are into cooling or baking.