The hypo castelnaui are a codominant mutation originating from wild specimens from the Mt Carbine area of Nth Qld (single factor animals are quite common there). The animals pictured are the double factor and were much harder to produce than they ever should have been (Murphy's law). The single factor animals have been around for years but Bob and co. put in the effort to finally crack the double factor.
Here's the normal , single and double together (getting all three to sit still in perfect alignment was just as difficult).