I'll be honest with you, I rarely ever get orders for the plates so I am not completely sure what is on the back. My better judgement would say that the black finish is on both sides and the logo is etched in on one side. They advertise that the plate will not rust or corrode so either way it should hold up well. I'd be happy to order one in and take a look at it before sending it out to you.
WRX Marque Plate - $27
Shipping would be cheap through the postal service, I can get one to you by Wednesday.