Understanding jQuery Ui Clones

Understanding jQuery Ui Clones

I am a little confused, I thought that once the clone's ID is changed to something different, it is no longer the same as the original. 

To my surprise the clone id is the same as the original draggable object's id although the clone's id had been changed.

Please look at my code below.
  2. var uiNewId = "test1";

  4. $("#obj1").draggable({
  5.     helper:'clone'
  6. });  

  8. $("#dropzone").droppable({    
  9.     drop: function(event,ui){
  10.         ui.helper.attr('id', uiNewId);
  11.         alert((ui.draggable[0]).id);
  12.     }
  13. });
Shouldn't the alert message show test1 instead of obj1? Also, ls the ui inside of the drop function referring to the original draggable object or is it referring to its clone?