Comment by russelg
I ran into this when implementing OIDC at work. One of my teammates wasn't able to login even though he just linked his google account. Turns out based on which browser session he was using, the same google login was giving a different sub. Super weird behaviour.
very skeptical about this - I believe they are two accounts.
It is possible to create two google account linked with same email address.
I think I need more proof they are actually same account. For example, changing the profile pic in one session is reflected in another session.