sounds like someone has no clue what they have. My first guess would be the same as yours, buff orpingtons. I'd just about bet the farm that's what they are and he was told they were 'buffs' and thought that was a breed.....I don't know. I have seen some sales for those too. When I asked they guy if they were Orpintons or what, he replied "No. Yellow Buffs"...haha! I didn't know if another breed was called that, kinda like Buff Orpingtons are just called Buffs sometimes.
or they could be a cross mix. As long as they lay, and all you want is chickens for eggs, you should be good to go