Last weekend I checked and replaced all of the taillight bulbs. It is indeed true that the dual filament bulbs will only fit into particular sockets because of the dual pin setup. So......if that is not the issue are there any other suggestions why the brake pedal would light the dash lights?

Thanks....

Yup. Bad ground connection at the rear of the car. Track the black wires from the lights and see where they connect to the body.

Despite the twin filament bulb (1157) having the offset bulb, people do manage to get them installed incorrectly. I've been driving at night and noticed that one of the tail lamps on the vehicle in front of me looks a bit bright. Then, when the driver hits the brakes, the tail lamp goes dim.

Just fixed that problem on my aussie 74 260 ,one of the stop/tail globes was incorrect it had a single contact stagered pin globe fitted.