i wouldnt risk it personally, haha. the whites will eat most things and mine take bugs bigger than their heads!!! you could just keep the smaller one in a seprate platic tank thing till its bigger . they are so hardy though it should be fine with a little water and humidity as im sure u know.
only you can judge whats going to be best, but ask yourself this, can he get the other frog in his mouth????? if not, keep em 2getha.