In the town my brother lives in there are a number of single family houses with two meters, one for normal electical useage, the other specifically for heating
We have a similar system in Britain which has gone under the name of "Economy 7" for many years.
The way it's done these days is to use a meter with dual-dials and a separate control connection (all electronic on the modern digital meters, but on older mechanical dials it actually operates a tiny solenoid to change the linkage).
There's then either a PoCo-owned timeswitch or a remote-controlled (telemetry) switch which changes the meter to the lower rate at night, generally midnight to 7 a.m. in winter, 1 a.m. to 8 a.m. in summer (i.e. 7 hours of cheap-rate, hence the Economy 7 name).
A contactor is also energized during the 7-hour period to apply power to a separate distribution panel which feeds storage heaters. The heaters are thus charged automatically at night, but the whole house benefits from the lower rate as well.
Night rate is typically around half of the normal day rate. At the moment I'm paying 6.75 pence per kW/h day and 2.87p. per unit night (plus tax).
An older variant of this system did actually use two separate meters, and was commonly known as "White meter" for the color of the cheap-rate meter. This had the same timeswitch/contactor arrangement to charge storage heaters at night, but the main distribution panel remained on the normal tariff all the time.
