I think those switches are usually marked which post is "I"gnition, and there will be 2 actual switches inside even if they both make contact at the same time, called a 'double pole single throw' switch .... for your functions, the difference is you don't want the ignition power to be lost if your accessories fry something, best to have it separate

Bill

Moved over to the Passing Lane

"When we tug a single thing in nature, we find it attached to the rest of the world" ~ John Muir
"When we tug a single thing on an old truck, we find it falls off" ~ me
Some TF series details & TF heater pics