To use Find Duplicates use the steps below:
Launch Drive Genius 4.
Select the drive you wish to scan on the left-hand side.
Select the Find Duplicates from the Clean Up section.
Click Start on the bottom right corner of the window.
Once the Find Duplicates scan is complete, a list of files will be provided that meet the criteria of the scan. Although the files may meet the criteria of the scan, it is your choice to remove any of the listed files. Be sure to thoroughly review the files to prevent removing any important files you may be using.
Mark the check boxes of any files you wish to remove, then select Slim Drive.