The connector has four inlets, high +, high -, low +, low -
Low - and High - are one single blade the Low + is connected by default with the high + being empty.
Pry the back of the bulb socket off and you will see the wire going to one side and not the other, Carefully pull out that connection and move it to the empty one. This will light the high instead of the low.
Note, if you don't want to mess with the socket you can bend the wires on the bulb to the other side to achieve the same effect.
Here's when I had mine that way. Passenger side was a normal incandescant bulb, the drivers side a 50w hallogen backup lamp, which, since the connectors were moved, would work in the front.
Both lights being incandsecant, with the socket modified & the bulb (on the passenger side) modified so both filliments lit at the same time.
Another angle, same deal