I've recently moved my guy up to small rats, and with that moved him to a 2 week feeding schedule. He's still gaining weight at a steady pace but not one that I'm uncomfortable with. As far as your female, you could probably ask for a small small (not a typo ask for a smaller small). In my experience every reptile store you go to who breeds/keeps their own feeders, call different sized rats different things. I actually did a side by side of a weaned from one place and a small from another and they were the same size. Doesn't mean that'll be the case for you, but it's worth asking.
I would try that instead of feeding two pups, you may get lucky and it'll be better for her.