เช็คค่าซ้ำ input file จาก การ create element ครับ

var i =0;
function create_upload()
{
	
	var my_list = document.getElementById('f');
	var my_file = document.createElement('input');

	my_file.setAttribute('type',"file");
	my_file.setAttribute('name',"file[ ]");
	my_file.setAttribute('id',"file"+i);
	my_list.appendChild(my_file);
	i++;
	
}
function remove_upload()
{
	
    var my_list = document.getElementById('f');
	var del_el = document.getElementById('file'+i);
	i--;
	my_list.removeChild(del_el);
	
	

}