I think it's going to be another multiple mutant allele complex like the lesser\butter\mojave\Vin Russo\phantom\special\hidden complex. Two different mutations of the same gene (a different gene than the het blue eyed complex with many more distinct mutations but like them in that yellow belly and specter-whirlwind seem to be different mutations of a common gene). I believe there have been a very few super stripe X normal breedings reported without any normals or super stripes so far to disprove the theory that yellow bell and specter-whirlwind could be different mutations of the same gene.