Items to Export are Less Than Number of Search Hits

I posted on this topic before but it has come up again.  I am running EV and DA 9 SP3.  The number of hits for a search (search criteria is To From only) is greater than the number of items for export.  Does this have to do with the search setting "include items already in review"?  It seems that the "include items already in review" option would produce a hit for items even if they are in review.  So I am trying to figure out why the number of items to export is less than the number of hits.  Is it because of de-duplication?  Is there a SQL query I can run to see what the difference is, de-duplicate or other?

Thanks!!