First time chicken owner! Got these little guys?/gals? Last weekend, was told they are Barred Rocks and 6 weeks old, now 7 if correct? Thing is two of them are smaller and darker than the other two, plus the smaller ones seem to still be developing there feathers (molting?). Could I have 2 different breeds? The seller was less than informative. So I'm kind of guessing on everything. Shure have been having a good time with them, very friendly chicks and fun to watch!