Ok, I found it:
$(xml).find('province').each(function(){
if($(select +"/[EMAIL PROTECTED]"+$(this).attr('id')+"]")){
select.append("<option value="+$(this).attr('id')+">"+$
(this).attr('name')+"</option>");
}
should be
$("province",xml).each(function(){
if($("select option:contains('"+$(this).attr('name')+"')").length==0)
{
$(select).append("<option value="+$(this).attr('id')+">"+$
(this).attr('name')+"</option>");
}
});
Just if anyone has the same issue...

