DirSync errors - Duplicate proxy addresses

We just encountered a DirSync errors related to one of our users. Error is about duplicate proxy addresses and UserPrincipalName value. I checked values and all looks good. Errors continue to occur event through manual sync. What am I doing wrong and how can I fix it?

This issue may occur if user objects in the on-premises Active Directory Domain Services (AD DS) schema have duplicate or invalid alias values, and if these user objects are not synced from the AD DS schema to Office 365 correctly during directory synchronization.

Please follow the instructions on the below link

Please follow the below link