Two meters day and night

I’m about to switch to Bulb but would like to know if there is one or two standing charges for having two meter readings (day and night)? In my previous flat we had related meters, one for heating and one for every thing else, I was told by a Bulb rep that there would be two standing charges for each meter. Is this the same with day and night metres?
Please answer ASAP as this will affect my switch decision.
Thank you!