You know that is a interesting questions. I have heard that they crossed them together to prove the marble eye isn't the same genetically so there was offspring produced that were heterozygous for both. What they actually did with the offspring is any ones guess. If they didn't cull then there are offspring out there with both genetics present. You figure they would breed the offspring together to see how both genetics influence the eye and even body together. It probably has been done but not spoken about to anyone outside a certain circle. It doesn't seem like it would be as hard to determine which is which as it would be if you crossed albino strains. I would love to hear from someone who might have more info.