They are different alleles that express in differing ways, so I guess to me it's still worth noting those differences when puzzling out what is going on with the chick in question :idunno
That is not a buttercup comb, or not pure buttercup anyway. Buttercup comb is split all the way from front to back. It's possible to get a comb similar to that from the buttercup comb gene being heterozygous (only one copy of the gene being present instead of two), but far more likely to get...