I've not worked with the leopard version (as far as I know) but IMHO regular pied has some pretty co-dominant tendencies. I've proven three 25% chance het pied girls and a 33% chance het pied girl and several possible het males along the way looking for the markers. Obviously I don't have leopard data to back it up but I could easily see it being another allele of pied that is further down the co-dominant scale.