SD+ - Migration aborted due to duplicate data.

SD+ - Migration aborted due to duplicate data.

Hi, we are running SD+ 11.0 Build 11009. When upgrading with ManageEngine_ServiceDesk_Plus_11_0_0_SP-1_0_0_Windows, we immediately see a warning 

Patch cannot be applied as duplicate entries are found when altering database tables. Refer logs for more details

The log itself states 
Migration aborted due to duplicate data. This may create issues during migration, so aborting now

Does any please know what is this error referring to? Any solution to this, please?

Thanks.
MG