I'll agree with Tad - they definitely do not remember their former partners.
What you have here is just 2 russian blacks that both hide a more recessive fur - and at least one of them hides siamese choco, maybe both.
The chances for both cats to throw their hidden fur like this is 25%. So statistically, if you mate them 4 times, you will get a siam.choc. just once. -But that's statistics... could also be you get 4 siamese chocos, or never get one
If a cat throws it's shown or hidden trait does NOT depend on if it has done it before, if it's partner does it or any such thing. It is simply random.
