Can they have puppies or not?

okay so let's start. my male dog happends to be fixed but my female is not. My female is having her period and it's very miner. Even though my male is fixed he just keeps humping her! Then she does the same! My male (when he's done humping) often licks just under the butt! I don't know if I can handle more then two dogs, but I'm willing to. And I don't want to break them up because I don't know what will happen! Say one or the other bites me... but they haven't yet. I haven't tried to break them apart! And when they finish their always panting extra hard. Then they do it Again!