How to check for the unused/duplicate elements in the selected report?

Use the Report Filters to check for the unused and duplicate elements in the selected report.

Go to the top of the Breakdown Table and click on the Filter button there:
filter-buttonThen find the Report Filter and select unused and/or duplicate elements.
The filters work based on the data from the Report Table.
N.B! You can always use the filter, even if there are no matching elements.