Android Google Signin without internet

Question

I followed the handbook to integrate the google signin in my android app and it works fine.

The only thing is that if I login using my emailID, and after that, if I re-install my app, and try to login again with the same email ID but without the internet connection, the google signin still works fine. But if I try to login with a different email, without internet, then that fails.

I am not able to understand how exactly does this work.