Suburban Water Heater electric heating element question

Suburban OEM On/Of Switches

GAS...Inside the RV
Electric ....Outside Compartment

Some RV MFGs (previous owners too) will ADD an additional switch Inside for the electric ----wired in series so BOTH would have to be on for the electric to work.
When there is an Inside switch for electric the outside one can be left on and the inside one used to control electric heating