Find duplicates of 2 columns

lfk73 

This also uses COUNTIFS but to prepare a report rather than highlighting cells.  Firstly, the process of testing every row against every other row is computationally very intensive.  The order in which the tests are performed is important for larger datasets.  

Since I use 365, I was able to filter the data, retaining rows with multiple matches for columns 5 and 1.  Where the records are complete duplicates, UNIQUE gives a single record for each.  If other properties differ both records are retained.

= LET(
    duplicated?, COUNTIFS(Column5,Column5,Column1,Column1) > 1,
    SORT(
      UNIQUE(FILTER(DataTbl, duplicated?)),
      {1,5},
    1)
  )