I ordered Rhode island red hens, they sent me 10 red which are what I ordered and 2 black. so What breed are the black baby chicks?
Might be austrolorps. Or not. Email a photo to the hatchery. You will either get a refund or a shipment of more RIR chicks, possibly six of them. If you did get austrolorps, don't be too unhappy. Their eggs are a bit larger than those of the RIR and they are good mothers, if you ever get a rooster.
You contact the company you placed the order with, to make sure what you ordered is what you got, mainly to correct the order and second to make sure the two that seem to not be correct, are not males instead of expected hens.