For wiring outlets, you can either wire them in series or in parallel. If in series, the outlets are wired one after the other. In this case, the wires from the plug would go to one outlet, and then wires would go from that outlet to the next. That means if the first outlet trips, then the second gets shut down as well. Wiring in parallel means the plug wires go to both outlets. This way they both have power and if one trips, the other still gets power from the plug.
Others can probably explain it better, but in the case of my box pictured above, I wired the hots from each receptacle to the hot from the plug, the neutrals to the neutral from the plug, and the ground to the ground on the plug.