From https://forum.ansible.com/t/logged-in-as-different-users-on-ansible-galaxy/1285

There seems to be an issue where a logged in users session can get hijacked.

From drodowic@redhat.com:

It seems like upon user login, the user sometimes gets the userID of an existing user. If the old user is still signed in, it now shows they are signed in as the new user.
my-namespaces lists all the namespaces of the users who had the same userID.
user-profile lists multiple github authentication providers

https://galaxy.ansible.com/ui/users/499/