Two electricity meters

Recently moved into a house which used to be two houses which have been combined to one in the laziest way possible. Each side of the house has two electricity meters, each with its own MPAN. The previous owners lead me to believe that they paid only one standing charge. When we moved in we switched from Eon (who the previous owners were with) to Octopus. We’ve just had smart meters fitted on both meters and whilst checking my account I’ve noticed two standard charges.

I contacted octopus who said they would look into it and get back to me in the next few days.

Is it possible to have a single standard charge whilst having two MPAN numbers? The previous owners were incredibly tight-fisted, so I can’t imagine they would have tolerated two standing charges. I did speak to Eon before purchase and whilst they couldn’t go into specifics on the account, they did indicate it was a single standing charge.