I want to breed them, but the fact that they are from petsmart makes seperating irrelevant. If I have a chance to get my hands on some of the more expensive kind that breed true I will definitely take special measures.
Not too much into guppy breeding, but I know enough to say that you would make more money by separating the strains (as said above). It's your choice, but some get a kick out of seeing what cool colors you can breed by throwing species together.