My best guess is that one of your " partridge " EEs lays a blue egg , and the Wheaten Ameraucana was the sire . The other pictured bird looks as if it may be rumpless ; not just lacking tail feathers . I sometimes see these cropping out in other's pics of their EE , and is just a natural evidence of their mixed ancestory . I had one EE guy in my group very much like him [ ETA: meaning the first roo ] but with a little less black . Since there is no possibility that same variety birds mated in your pens , all resulting chicks are EE in my opinion .
One other observation , any of those chicks born with a chipmunk pattern cannot be wheaten colored inspite of their adult visual pattern
