x2 on what CochinBrahmaLover and poltroon said.
A lot of people take mutt offensively but honestly, in all reality, it's a word and not an insult. Fact of life is that they are mutts 90% of the time and there's no way to get around that. Hatchery stock especially has been obviously out-crossed to increase egg production/vigor. This is coming from someone who, for quite some time, bred f1 Ameraucana cross EE's. There's nothing wrong with EE's, but I don't make them out to be something they aren't. Which is a breed. They have no standard (at all), aren't recognized by the APA, etc. How can it be a breed if the breeders don't even work toward a standard or even a general idea? There's not even a singular egg color that they are bred for. Blue and green are the most valued, yes... but they're called Easter Eggers because they can lay just about any color egg.
Making the connection that they are to Ameraucanas like what hatchery stock is to heritage stock is completely off imho. If I purchase an EE from a hatchery, I have no clue what color it's going to be, what conformation it's gong to have, what color eggs it's going to lay, what sort of personality it's going to have. But, if I buy a RIR from a hatchery - I can expect that bird to mimic stock from a quality breeder, just to be of lesser quality. But expecting anything like an Ameraucana from hatchery stock EE's is setting yourself up for disappointment.
If the birds met the standard other than color... had the body type, right shank color, pea combs, muffs and beard, layed blue eggs... you can argue that the bird is non-standard color Ameraucana. After all, project Ameraucanas actually are Ameraucanas that just haven't had their color accepted into the books. But like I said previously fact is very, very few EE's are mixed color because two different color Ameraucanas were bred together.