In this diagram, two receptacle outlets are wired in the same box with a separate 120 volt source feeding each. Three-wire cable runs into the box. The black and red wires are hot and each is connected to one of the receptacles. The white, neutral wire is splice to each outlet so they share the return path. This is appropriate for standard duplex receptacles, but should not be used for GFCI receptacles. GFCI’s must have dedicated neutral connections to work properly.
This page contains several diagrams for 2 or more receptacle outlets in one circuit. Wiring for multiple ground fault circuit interrupters (gfci) and standard duplex receptacles are included with protected and non-protected arrangements.
Here 3-wire cable is run from a double-pole circuit breaker and split to supply 120 volts to two sets of receptacles. The neutral wire from the circuit is shared by both. This wiring is commonly used in a 20amp kitchen circuit where two appliance feeds are needed, such as for a refrigerator and a microwave in the same location.
This diagram is similar to the one above, but with the electrical source originating at the fixture. Three-wire cable runs from there to the controllers. The neutral wire from the source is spliced directly to the white wire on the fan/light. The hot source wire is spliced to the white on the 3-wire cable and then spliced to the input wires on both controllers at the other end.