Error Field 'subject' does not match subject from previous authentication. while trying to over-write current user

[yokaipooh]

1: login as usual
2: use postman to create an oauth 2 login request
3: access the request url
4: login with different account
5: got error above and when move on the site I got the user's data from 1st step
Do anyone have a way to over-write the current user?
cause after login success with prompt=login, I call oauth2/auth/requests/login/accept got the error above