Would my cat know another sister was not the original sister he had?

My neighbor has a litter of kittens which is Ck, my Tom’s, younger sisters and brothers two generations down. There is a female kitten that looks almost like his sister Splotch, which we lost a SUV. Though his newest little sister looks a lot like the sister he lost, would he think or believe it was her it would the smell or some innate ability tell him it was a different female cat?