jquery - Ajax sends two files at one time through one onclick event in JavaScript -

jquery ajax seems sending 2 requests @ once when use onclick event javascript in tag. click once, , seems ok, when change id value invalid id value, sends 2 requests php file. think problem may caused browser caching javascript code. here's javascript code i'm using generate query:

function unlike_image(id, image_id, obj) {     var url_unlike_image = base_url + 'profile/unlike_image';      $.ajax({         type: "post",         data:         {             user_id:  id,             image_id: image_id         },         url: url_unlike_image,         success: function(data) {             if (data.status=='error_exists') {                 alert('this image not exists');             }              if (data.status=='success') {                 //like = - 1 view                 var str = $(obj).next().text();                 var n = str.length;                 str_like = str.substring(1, n-1);                 var number_likes = parseint(str_like) - 1;                  $(obj).next().text('('+number_likes+')');                 //change event click unlike                 $(obj).text('like');                 $(obj).attr('onclick', 'like_image('+id+' ,'+image_id+ ',this); return false');             }          }     }); } 

after changing true id wrong id, check website traffic, see 2 instances unlike_image called. first true id, , second wrong id.