Ok, yes. I don't know what MMcM hatchery but according to the they are from ameraucanas but they definitely don't look like purebred ameraucanas. but I have no idea what they're doing with their birds. Maybe you could get on a chat with someone that works there.
Ok! https://www.mcmurrayhatchery.com/ameraucanas.html
No, those they have a separate flock of BBS ameraucanas so they would be purebred. Here's a link to those ameraucanas: https://www.mcmurrayhatchery.com/blue-ameraucana.html
Sorry, but they do. They have purebred ameraucanas in their mixed ameraucana flock and their offspring are more than likely EEs. Trust me My profile name is @AmeraucanaHank!