They could be Speckled Sussex, though not breeder quality. My four week old SS chick I bought at a livestock auction has similiar markings to your second bird.
I'm so confused, I wish there was a definite way to tell(not that it ultimately matters, we love them no matter what).
I really thought they're two different breeds because of how different they look. I somewhat agree on the partridge rock for the chipmunk marked one, but every time I look through pictures online, I can't rule out partridge rock, welsummer, or SS for either one of them. do you think it'll be easier to tell when they get older?