As suggested you probably have an inverter.
Questions.....
What switch is off on xxverter (be it converter or inverter)?
And with battery disconnect switch off then neither should work (charge or take power from battery) so if you have 120V AC power at outlets then suspect battery disconnect switch is not turning off or inverter is bypassing the battery disconnect switch.
On Edit: Because of 2oldman's post
Nomenclature........Off really ON or OFF is OFF????
My disconnect switch is labeled OFF to disconnect battery and ON to place battery in service.
Can't anything be 'standard' when it comes to RVs :B