You can sort the duplicate result report by clicking any of its column headers. Click once to sort by the column in ascending order, again to sort in descending order.
How Sorting Works
Duplicate File Detective implements a highly specialized approach to sorting duplicate search results. Specifically, sorting is done at the duplicate file group level in a manner that ensures that duplicate groups are kept together within the results report.
Say, for example, that you sort the current duplicate search results by size in descending order (so that the largest files are near the top of the report). First, the files within each duplicate group will be sorted (by size in descending order), and then the duplicate file groups themselves will be sorted in the same manner, using the size of the first duplicate file within the group (which will be the largest due to the previous step) as the sort key.
If that seems confusing, please spend some time playing with sorting duplicate search results to see how this works. The key concept to remember is that Duplicate File Detective will always keep duplicate file group entries together during sorting operations.