I wonder if two different dogs got to the female when she was in heat. It's possible the labby ones are purebred and the black-masked ones are "half-breeds". Nigel's litter had two different fathers. Strange phenomenon...
Cute pups though either way! I bet mastiff/lab crosses would be cool dogs! Or whatever they are!
I think Rebekah and I are sharing a brain today. I was going to say the same thing. I bet she bred with 2 different dogs - and that's probably why he's giving them away.
It's not such a "strange phenomenon", though. This happens with dogs all the time if they are allowed to free-breed.
They may be black-mouthed cur mixes, too.