There are many best tools available for removing duplicate Outlook contacts, but I can suggest the best tool becouse I'm also using it. SO you can use a TrustVare Outlook Duplicate Remover for removing duplicate contacts from Outlook files. This software quickly scans Outlook files like emails, contacts, notes, tasks, calendar, etc, finds duplicate items and removes them without any errors. The tool handles a lot of duplicate Outlook files without downloading any application. The software has a simple users user-friendly interface for non-technical usres. The software supports all Windows OS versions like 11, 10, 8.1, 8, and 7. Users can use a free trial before buying this tool. After removing this tool, it will give you a preview and the results.