When you say "electric usage," do you mean 120 VAC electric usage from shore power, or 12V usage from the batteries? Are you connected to shore power?
Particularly if it's battery power only and no shore power involved, do you somehow have an inverter set up such that it's driving a converter or battery charger (perhaps the other inverter in charge mode if it's an inverter/charger)? Do you have an RV fridge on 120V rather than propane? Those would be my initial guesses.
If 120V power, possibly it's going through a double conversion when you aren't expecting it to, though that shouldn't double the power usage overall.