
Nature has designed species with litters to have built in wastage, even though ti is upsetting, some of the fertilised eggs don't implant, some fail to find enough room or make have failing placentas, and are absorbed, some get so far but not as far as birth, some don't manage the changes at birth, or were too weak from competition in the womb to survive.
These two were both very small compared to the rest of the litter (I had two stillborns like that in my most recant litter), so I would not worry too much over the remaining strong ones unless anyone is failing to gain weight.
Sods law of course the ones lost were the bitches, and you only now have one bitch. though of course she could still well be your pick of litter.
In my breed two top winning litter-mates and influential producers were the only two pups in a litter, one of each sex.