The launcher keeps access tokens per profile, not per account.

This means that If I have two profiles (1.5.2 and 1.6.2) using the same account (tehbeard), when I switch profile (e.g. to test our dev server (1.6.2) after playing on our production server (1.5.2) ) the access token in that profile (1.6.2) is invalid, meaning that I must logout on that profile and then log back in, which then invalidates the 1.5.2 profiles token.