Could also be something like what is called a "marketer". Where I live, we have multiple gas companies to choose from. That doesn't mean each house as 4 lines coming into it. All the lines are serviced/owned by a single company, if there is a service call, it's that company's trucks that roll. But you don't buy from them, they are a wholesaler only. Instead you buy from one of the marketers whose job it is to provide front-line support, billing/payments, etc.
Could the two be on in the same? Sure, electricity is a good example of something usually municipal where it's owned and operated by the same company. The marketer concept allows some level of competition (there are price wars across companies for natural gas where I live, for example), where you also don't want redundant infrastructure.