I thought single combed Wyandottes popped up more in hatchery stockIf you cross pure for pea comb to pure for rose comb you get all walnut combs.
If the Wyandotte only carried one rose gene that cross would be 50/50 between producing pea or walnut.
Only mentioned that since its not uncommon to get wyandottes that only carry one rose gene. Hence why single combs pop up in their lines.