That would mean the label is incorrect. Obviously there is no way to tell that without inspecting the supply. If you unplug the power cord, what reading do you get if you measure resistance between pin 1 and 2? If this is a very low value ( < 1 Ohm), then they are likely shorted at the power supply end, and very unlikely to supply a different voltage. My guess, based on the label, is that they just used two pins in parallel for current carrying capacity.