[Talanes]

I have the opposite experience, where I (usually) am more myself when I'm alone.

Which I partially attribute to the inner voice feeling like the main consciousness. There's often a disconnect of having to semi-verbally think through something before responding. It takes a conscious effort to switch to speaking naturally without the mental rehearsal.

Edit: >You have an actual dialogue with another entity that is also you?

If I'm working through an idea in my head or trying to catalogue my knowledge of something, it's often framed as a one-sided conversation with someone in my life. Sometimes because it is something I'm likely to speak to that person about, but just as often I know it's just irrelevant junk I'd never actually burden another human with listening to.