How to handle multiple identities?

I have two main private PGP keys: one for business, one for personal, each with multiple identities. I can live with picking just one email address (so this is not a duplicate of #105), but how should I handle my two keys?

Right now, my first idea is to just create another keybase account, but that seems suboptimal too. They do both belong to the same person, and the same github account.

No files, tests, or entry points are mentioned. Start by reviewing the existing account and key-management behavior, then define the supported approach for representing both keys under one person and what documentation or implementation would be needed.

Written by the indexing model from the issue text.