For one of my client who is on AX 2012 R3 CU8, We started getting this error on 2 of our PROD AOS Event Viewer - "Duplicate request to load user mappings detected"
After some initial troubleshooting, found out this binary hotfix in LCS, which fixes the following issue
Once you download the hotfix, just run it using the AXUpdateInstaller. It takes few mins depending on your AOS topology and servers to run this update.
Word of caution - As with any hotix (be it application or binary, always test on your TEST instances and leave it running for couple of weeks, monitor and only then deploy the hotfix to your PROD)
Notes form the hotfix description in LCS:
After you apply the kernel hotfix KB3133925, when you execute the Automatic role assignment function, you receive the following error message:
"Duplicate request to load user role mappings detected."
DESCRIPTION OF CHANGE
The changes in the hotfix add the "AutoSkipXdsGeneration a_SkipXDS(ip);" line to start of AuthenticationContext.LoadRoles to ensure you can execute the Automatic role assignment function without any error messages.