[jQuery] Change Event Firing Twice

[sobencha]

My problem is that I seem to be having a change even firing twice.
Here are the details....

I have several checkboxes (input type="checkbox") all containing a
class named "metaABOCode".  Whenever one is ticked or unticked (hence
the change event), I want to grab some data via a json ajax call to
populate some content.  Everything works brilliantly, except for the
fact that it seems as though the code below is being called twice
(resulting in two ajax calls, etc.).

Any ideas/suggestions as to why this is happening? Feel free to let me
know if anything else is of glaringly poor form as well!

Thanks a lot; appreciate any help you might be able to provide.

The code (and using 1.2.6)...

$('.metaABOCode').change(function() {
                                $('#metaDistributorCodeTable 
tr.metaDynamic').remove();
                                if (!$(this).is(':checked')) {
                                        
$('#meta_abocode_all').removeAttr('checked');
                                } else if ($('.metaABOCode:checked').size() == $
('.metaABOCode').size()-1) {
                                        
$('#meta_abocode_all').attr('checked','true');
                                }
                                var str = '';
                                $('input.metaABOCode:checked').each(function() {
                                        if ($(this).attr('id').substring(13) != 
'all') {
                                                str += 
$(this).attr('id').substring(13) + "-";
                                        }
                                });
                                
jQuery.getJSON('/cms/page/meta/distributorcode/' + str,
function(json) {
                                        var html = '';
                                        html += '<tr class="metaDynamic">';
                                        html += '<td><input 
id="meta_distributor_all"
class="metaDistributorCode clickable" type="checkbox" /></td>';
                                        html += '<td><span 
style="font-weight:bold;">Select All</span></
td>';
                                        html += '</tr>';
                                        for (var i=0; i<json.length; i++) {
                                                html += '<tr 
class="metaDynamic">';
                                                html += '<td><input 
id="meta_distributorcode_' + json[i]
['sp_code'] + '" class="metaDistributorCode clickable"
type="checkbox" /></td>';
                                                html += '<td>' + 
json[i]['sp_name'] + '</td>';
                                                html += '</tr>';
                                        }
                                        
$('#metaDistributorCodeTable').append(html);
                                });
                        });