just what you said, wired 2 sockets together - the way the rear lights work is the 2 wire bulb is taillites [same as front parklites] on one wire, brake and turn both on the other wire, when signal is on it uses the brake filament, brake light gets power thru the signal wiring ... the extra socket is excess, wire the dual filamet socket up according to the shop manual wiring diagram and ignore the other
Bill
