Instead of a single AMB (asynchronous message bus) being created when a user logs in, the message gets registered multiple times, which causes the instance to request authentication either by session timeout or login credential request dialog boxes.
Steps to Reproduce
Start a browser session and leave it unattended for two hours (assuming your instance has a session timeout of 60 minutes).
Multiple session timeout dialog boxes or requests for login credentials are displayed when the browser times out more than twice.
Log out before leaving a browser session unattended and close the dialog boxes if they appear.
Related Problem: PRB709024