Right now in the milestone summary the shown defects are tied individual test cases. So if a defect is tied to multiple test cases the list shows a bloated number of defects.
While helpful to know what test cases are impacted by defects. If a user is looking for a summary of defects, as in total of defects. The count and report can be very bloated.
If there was a way to filter or an option to only show unique defects especially at the summary section. That would give a clear image of “this # of defects are in this milestone”. This could also be part of the report. Where at the header it shows the total number of unique defects. And then in each run report it breaks it out to show each affected test case in those runs.