Update:
My rare chick is not a Dominique, as I had stated earlier. His comb is more developed now at nine weeks of age and it it obviously a straight comb. After browsing through the catalog again I'm thinking he might be a Cuckoo Marans. He is very cool and gentle. He wasn't as big as the other cockerels at first (they're all Speckled Sussex.) Now he's about the same size as the largest cockerels. He has one tiny wattle and one big dangly one, a flaw for a show bird but pretty darn cute for a pet.
...just received another bunch of chicks today with another rare breed bonus baby. This one is the blackest chick I have ever seen. He has a little lighter coloring on his feet, and a tiny white spot on his throat. He is long-legged, tall, and skinny compared to the Buff Orpington fluff balls. There is no chick pictured with this much black in their rare breeds section of the catalog. The closest thing is one of the black Blue Andalusians. (The chicks come out 50% blue, the rest splash.)
Still not sure what these babies are, but it is fun trying to guess! Now I'll have to breed the oddball Marans looking rooster to something to see how dark the eggs come out, and breed the black bird to a white Blue Andalusian to see if the chicks come out blue. I got into this thinking meat & eggs and it is turning into a chicken obsession!