title: Is FCM (firebase cloud messaging) Token for one device or for one account?
body: <p>I want to store FCM token in  my android app user's table in database when user register to the app . When i want to send notification to specific user then i will fetch Token from corresponding row and send push notification.But i am confused that whenever app user logout from his app and register new account from same device ,then there will be two row and hence two Token for same device on database. How to handle such case? What happen to old Token in device? please anyone can help me?? </p>