Updated: Aug 9, 2019
When you save an attachments using #Office2SharePoint for #Outlook and it already exists in the SharePoint library, Office2SharePoint gives you the opportunity to either Ignore, Replace or Rename the file. If you select Rename, the files will be saved with the name of the file along with "" in the end. In the video below, you can watch an example of renaming a file in Office2SharePoint for Outlook.
More information about Office2SharePoint