The Find Duplicate Files box is above the Duplicates List Browser.
When the box is checked, SpaceMan 99 will scan for both duplicate files/folders and folder size when the Scan Folder command is selected. Any duplicate files found will be shown in the Duplicates List Browser.
If the box is not checked, then SpaceMan 99 will only scan for folder size. If you only want to scan folders for size, it is much quicker to turn off the Find Duplicate Files option.
Key: F2