Yes they can! Female cats mate with many different toms in the same heat cycle and they ovulate new eggs each time. This leads to superfecundation: one pregnancy from more than one mating.



What's interesting is that you can actually detect superfecundation by examining the kittens in a litter. It's possible to calculate the date of a kitten's conception (within a day or two) from the date when its first adult teeth come in. So if two littermates start losing their baby teeth on different days, then there's a decent chance they have different fathers.



I learned all this on one of my cats' many kittenhood checkups. By looking in their mouths the vet was able to tell me that the male is a week "older" than his twin half-sister.

You can also tell because the kittens will look different. Most of the time, kits will resemble their father. So if, for example, if you have two kittens that are brown tabby and two that are tortoiseshell from the same litter, then the mother has mated with more than one cat.