Cats are a close example of when nature works different, although not so sure about the selection process and the inner workings of the conscience of female cats but the nature of female cats is to keep mating when in heat, if not getting impregnated during heat she will return to normal for a short period of time but soon come into heat again for another round.
When in heat the cat releases several eggs and the eggs can be delayed to eachother within the same heat. Thus when the litter of kittens do come, it's quite common for them to have different fathers from another. Again, not sure about how aware the female cat is of this. Maybe she's wired to let go off her eggs when sniffing urine off territory markings from the strongest of males.
One father?
So comes another question in mind, about urine smell and what animals detect from eachother via their urine scent; if urine means so much as often depicted, simply why not evolve into leaving a strong attractive smell regardless of circumstances?