stuff.js

 <script>
       $(".original tbody").on( "click", "tr", function() {


           var row_id = ($(this).attr('class').split(' ')[0]);

           if ($('.selected .' + row_id).length > 0) {
            // do nothing, probably should use .not() up there
           } else {
            $(this).addClass('cloned').clone().prependTo($('.selected'));
           }
           calculate();
       })
       $(".selected tbody").on( "click", "tr", function() {

           var row_id = ($(this).attr('class').split(' ')[0]);

          $('.original .' + row_id).removeClass('cloned');
           $(this).remove();
           calculate();
       })
       
        var calculate = function () {
            var sum = $('.selected tr td:nth-child(2)').toArray().map(function (td) {
                return $(td).text();
            }).reduce(function (sum, i) {
                return sum + parseInt(i);
            }, 0);
            $('.total').text(sum);
        };
        var t = $('table');
        var c = $('.column');
        calculate();

        $("#original").tablesorter( {sortList: [[1,0]]} );
        $("#selected").tablesorter();
  </script>