Did you know it's possible for cats in the same litter to have different fathers? Yup - it can happen.
My girls are from the same litter, 2 sets of twins. Two are grey and white females. Two girls are I think they call them brown mackerel? Their mom was a calico. (One of the mackerels went missing at 1.5 years old but we are fairly sure a neighbor took her in.)
Toffee and Fudge were from a litter of four and all kittens were identical. Given the fact that they were born in a feral environment, I think it's pretty remarkable that all four survived (their two brothers were adopted to a different family together) and also all four looked exactly the same. I remember the shelter saying they were a special case in the terms of this, too - they were little fighters!
My last two cats were littermates. Their mother was a white Persian who had gotten out, in an area filled with street cats. Belle and Beau looked alike, so I suspect they shared a father. The other kittens were various colors.