They are actually a bit darker, the flash made the chicks look lighter than they are.
They are almost completely black with yellow on their bellies and neck and one has some by the eyes
I also got a barred rock chick the same day and they don't look to be the same breed. The feathers on the wings are almost completely black vs. the barred rock, who's is already turning grey/white/black ish
They also have dark legs but not completely, there's some light spots on their legs too