I have always fed one mouse at a time for the reason that rodents, especially Rats, can be aggressive. My Last BP got tore up pretty bad by a rat and had to get stitches at the vet. It was a bloody mess. Ever since then I have always been careful to monitor the snake's progress Until I at least I know the rodent is dead. I have even seen rodents bite a snake while in the coils and the snake retract and let go and not eat. That is what happened to my last BP on one of his feedings. Best I can figure, I saw him strike the rat and coil around him and then I left the room. Came back about 5 minutes later and the rat was alive in one corner and my snake coiled and bleeding in the other. I know this is what must have happened and I've made sure never to leave when they are feeding. If one rat or mouse can do that much damage, think what a 3 on 1 battle could end up like.