Issue:Tablesortcol, same value in two or more rows, wrong data

Description:	using tablesortcol when there is same value in several rows results in discarded rows
Extension / Version:	DPL   /   1.7.4
Type / Status:	Bug   /   open

Problem

There is something strange (or is it an expected behaviour?) when the column specificated by tablesortcol parameter contains the same value in different cells: only one row is displayed for each value, but the PAGES magic word returns the sum of all pages selected. You can see some examples at [1] , where also the distinct parameter is tested. It seems a bug, but probably this can be related to my low experience in DPL...