You're welcome. If your chipmunk striped chicks were labeled as Plymouth Rocks then they somehow ended up in the wrong bin. They are definitely not Plymouth Rocks.
I can't get the pic to enlarge for a better look, but the only one of those four that could possibly be a Barred Plymouth Rock is the black one in the very back and if it doesn't have a white spot on top of its head (I don't see one in the pic), it's not a Barred Plymouth Rock either. The light...