Question on breed

[chixrus2013]

I have 8 four week old chicks, 2 buff orpingtons, 2 barred rocks, 2 ee, and 2 NH reds. Well, it was supposed to be 2 NH reds, but, now I'm not sure. One of the NH reds has some dark feathers coming in on her neck. NH reds don't normally have those and the other one I have doesn't have those dark feathers. I'm wondering if I have something else and not a NH red. Would love any input to tell me what breed it may be.

 

[TheOddOneOut]

Red sex-link?