[jQuery] Jquery makes two ajax requests in one!!

[Skyblaze]

I have a strange problem. I have to do an ajax request after a select
box changes (change event) so i have the following code:

$('#comprensori_id').change(function() {
                        var comprensorio_id = $(this).val();
                        $.ajax({
                                   type: "GET",
                                   url: "",
                                   data: "comprensorio_id=" + comprensorio_id,
                                   success: function(data, msg){
                                $('#comuni_id').empty();
                                $('#comuni_id').append(data);
                                   }
                                 });
                });


the problem is that when i change the select box selection my browser
makes two consecutives same ajax request and i can't figure out
why...this is very strange