The brake switch does indeed have two circuits, but one is used for the DME as a switch integrity test circuit.
It's a belt and braces test that sends a second simultaneous signal to determine that the pedal is, or is not, actually pressed.
The other switch contacts link all other circuits together, including roof and brake lights, so if brakes lights are on then roof should have +12v as that side of the switch is working.
It's a belt and braces test that sends a second simultaneous signal to determine that the pedal is, or is not, actually pressed.
The other switch contacts link all other circuits together, including roof and brake lights, so if brakes lights are on then roof should have +12v as that side of the switch is working.