They have four screws so that you can run power to another receptacle off the second set. It makes no difference which set you connect your wires to. For the switched outlet, you need to break the little brass tab off that runs in between the upper and lower screw sets.

What are the screws on the side of an outlet?

On each side of the receptacle is a pair of terminal screws. The upper screw is connected to the upper outlet, and the lower screw services the lower outlet. A thin, metal break-off tab connects these screws.

How many screws are on a receptacle?

Standard outlet receptacles will have a total of five screw terminals: two silver-colored screw terminals for attaching neutral circuit wires, two bronze or copper-colored screw terminals for the hot circuit wires, and a green screw terminal fixed to the strap of the receptacle, which is used for the bare copper ground ...