Jquery Sortable Update Event can called only one time?

Jquery Sortable Update Event can called only one time?

Hello. I'm trying to make category changes with Jquery & Php. I have no problem with it. My problem is, when the update event is called, it returning 2 results. 1 result for Dragged Parent, One result for Dropped Parent. I wanna call only dropped parent's id. Here is my script: 
  2. $("#gallery ul").sortable({
  3. connectWith: '.dropBox',
  4. scroll: true, 
  5. scrollSensitivity: 100,
  6. helper: 'clone',
  7. containment:'#gallery',
  8. accept:'#gallery > .photo',
  9. revert: true,
  10. update: function(event, ui){
  11. var params = 'category=' + $(this).attr('id') + '&id=' + ui.item.attr('id');
  12. $.ajax({
  13. type: 'POST',
  14. url: 'processData.php',
  15. data: params,
  16. error:function(){
  17.                  alert("Error!");
  18.                 },
  19.                 success:function(data){
  20.                  $("#serverResponse").html(data);
  21.                 }
  22.          });
  23. alert(params);
  24. }
  25. }).disableSelection();

Please help...