That's happening because you found a corner case that Persona isn't handling. Oops.
The Persona team needs to sit down and figure out what should happen when you do that. I've filed a bug to track that discussion: https://github.com/mozilla/browserid/issues/3332
I'd appreciate it if you could chime in with what you think the correct behavior should be, and why.
For context, Persona initially used loggedInUser
only for determining what callbacks to invoke automatically during page load. After that, it was more or less ignored. Which is why you're seeing calls to onlogin
, even though the selected identity matches the current identity.