Power Supplies: Do Redundant Supplies Use More Power Than A Single Supply

do dual power supplies use more power than a single supply?

E.g. Say I have a server than uses two amps, powered by a single power supply. Now if I switch to a dual supply (and say each supply has the same efficiency rating as the single), does my server use more power? How much more?

My simple view of this is that it probably does, but maybe not much. The second power supply consumes some power itself, but since its not under load, it doesn't consume much. Therefore, my server with redundant supplies might use 2.1A or 2.2A.