A more interesting question is if the patient complains of two selves, does the doctor get to bill them double?

You go to the dentist complaining of a toothache, but the doctor doesn't work on the "ache" as if that was something he could put on his workbench and operate on. He works on the tooth so that you can get back to using it again.

In the bigger picture, doctors help people get back to living the way they need and want to live. A co-worker had her hip replaced not just because it was painful, but so that she could do things she hasn't been able to do like put on her own socks.

That was the sense I meant of treating the patient and not some inner state. Anyway, if the patient is suffering from a mental disorder, why should the report of multiple selves be taken as accurate reading of something going on inside the person? The report is valuable, and may lead to successful treatment, but we don't have to believe the literal interpretation of it.