I have noticed that too. Males are pathetic feeders compared to females. Another thing I have noticed is that although care sheets say male dubias can't fly some that I have held have jumped managed to fly. Not just flutter but fly across the room while going up at the same time. Don't know if I have made super roaches or if they all can do it.
Just a note: if you feed the males off clip the wings off. There no nutritional value in those darn wings and just a hassle for them to digest.