How it works (based on experimentation):
- a Libravatar account (login):
- has zero or more profiles.
- has zero or more avatar images
- each profile corresponds to an email address and an avatar selected from those managed by the account
So: say you're in Liberapay trying to set up a new team, and you want to give it a different avatar from your primary account, you add a new email address at Liberatar and give the team that email address for fetching the avatar.