According to the documentation, we know that the client can send its ID Token, or Registration Token, to the application server to notify the client that it is logged in.

https://firebase.google.com/docs/auth/admin/verify-id-tokens

I would like to know if this token can have duplicate values? I know it is similar to a JWT, which contains information such as uid, issue time, etc. If the same account logs in at the same point in time, is it possible for different devices to generate ID Token with the same value?

CodePudding user response：

No it is not possible. Application installation is one of the things that change.

Assuming you mean the FCM token, used to send e.g notifications.