No, the females will most likely fight and babies could get harmed. Females really should be separated singly when they are pregnant/birthing/rearing babies. They should also be given at least 1-2 weeks after the babies are fully weaned(4-5 weeks) to rest and gain back her weight before being bred again.

The female rat that is in with the male now, is already pregnant again. That is depleting her resources exponentially right now. Babies nursing still, babies forming inside taking her reserves, and her own body requirements. That's alot of strain on their bodies and really isn't the best for her. She most likely won't live very long if you continue that regimen with her.

It would be best to separate her now, before she gives birth again(which could be before these babies are weaned). She doesn't need to get pregnant again until after this 2nd litter(that she is pregnant with) is weaned and she's given a week to two weeks off(without babies). The litters will be bigger in number, babies will be heavier and healthier, and the mom will have adequate reserves to properly provide for them(and not run out of milk).

Keep one of the male's sons as a buddy for him, while he's not in with either female. He'll be a happier rat for it.