Huh?
If the cells didn't split properly and separate, you get siamese twins, or conjoined twins. They don't resorb into each other and become one animal.
Hix
Another name for this is a "chimera". Where 2 separate embyo's get pushed into eachother early in development and the resulting offspring has 2 lots of genetic material in certain parts of its body. Thats how paradox albino's form, Piebald is different to paradox albinism