Lamps are not limited to a single bulb socket. Lamps that have two or more bulb sockets can produce more light, and depending on the design, may be operated with different numbers of bulbs on or off, allowing for different amounts of light. Wiring a lamp with two bulb sockets doesn't present any more difficulties than the wiring involved in a single bulb socket lamp.
Cut two lengths of lamp cord, each long enough to reach from the socket locations to the base of the lamp when routed through the lamp. Pull apart the two leads on the ends of each lamp cord and remove 1/2-inch of insulation from the ends of each lead.
Loosen the two screws on the base of each lamp socket with a screwdriver. Attach one lamp wire lead to each of the screws and tighten. Push the other ends of the wires through the lamp, then place the sockets onto the lamps and screw them into the threads on the lamp with your hand.
Twist together one of each lead from the two sockets so that you combine the four leads of the two lamp cords into two leads. Pair the bare ends of the lamp cord that runs to your plug with the two leads from Step 2 and place a wire nut over each joint. Twist the wire nuts to secure the wires together.