Well, I have bred a couple litters before. How old are the bunnies? If their eyes just opened... I'm guessing 1 1/2-3 weeks? The one without a tail I've never heard of... maybe he's just got a small one that you can't see as well.

Make SURE you seperate the bunnies male from females at 12 weeks of age. They can get each other pregnant. Since the female is pregnant again, do NOT let the male rabbit near the female. Rabbits can get re-pregnant and have 2 litters that are 2 different ages inside her.

Good Luck, and if you have anymore questions, please PM me!