Owners have lived here for 50 years. What would the Lt meter be for? Federal Pacific panel is behind the rt meter in main house!
Looks like they upgraded the meter on the left with a newer model on the right.
Submetering something like an electric water heater.
Once upon a time, there were two meters. One was for the water heater. Can’t say why they did it that way, but seems it was two lines on the bill or there were two separate bills. May have been different rates.