List1    List2
 AAA     111
 BBB     555
 CCC     999
 DDD     777

List1    List2
 AAA     111
 BBB     555
 CCC     BBB
 DDD     999
         777

drop: function(event, ui) {
         $(this);
         $(ui.draggable.**clone()**).appendTo($(this));
      }