I think there is a kind of natural rivalry and jealousy between women that increases the more similar they are??? If there is dramatic differences, the women can say they are prettier, or sexier, or blond, or brunette, or have better legs, or better butt, or better breasts, or whatever. But if they are with their exact doppleganger, how do they tell themselves they are the better woman? Pure speculation on my part, but a theory.