SELECT <columns to be checked duplication>
     , MAX( <col-1> ) AS <col-1>
     , MAX( <col-2> ) AS <col-2>
     ...
     , MAX( <col-n> ) AS <col-n>
     ,    CASE WHEN COUNT(*) > 1 THEN 'Dup ' ELSE '    ' END
       || CASE WHEN COUNT( <col-1> ) < COUNT(*) THEN ' 1' ELSE '  ' END
       || CASE WHEN COUNT( <col-2> ) < COUNT(*) THEN ' 2' ELSE '  ' END
       ...
       || CASE WHEN COUNT( <col-n> ) < COUNT(*) THEN ' n' ELSE '  ' END
       AS flags
 FROM  <your-table>
 GROUP BY
       <columns to be checked duplication>
 HAVING
       COUNT(*) > 0
   OR  COUNT( <col-1> ) < COUNT(*)
   OR  COUNT( <col-2> ) < COUNT(*)
   ...
   OR  COUNT( <col-n> ) < COUNT(*)
;