ช่วยด้วย ครับบ Upload file PDF ซ้ำอันเดิมไม่ได้ ทำยังไดีคับบบบบบบบ

/* function up load files*/
function upload_files($elementname, $folder, $newname){
	$type = substr($_FILES[$elementname]['type'],0,5);
	
	if($type)
	{
		$file_extension = substr($_FILES[$elementname]['name'],-3,3);
		//$filename = "$newname.$file_extension";
		$filename = "$newname";
		$destination = "$folder/$filename";
		
		if(file_exists($destinaton))
			unlink($destination);
			if(copy($_FILES[$elementname]['tmp_name'], $destination))
				return $filename;
			else
				return "none";
			
		return "none";
		
	} /*End function up load file*/
}
	
	/* Delete old pdf file */
	if($_FILES[pdf_file]['name'] && $_POST['old_pdf_file']){
	
	$destination = "../../../pdf/$_POST[old_pdf_file]";
	
	unlink($destination);
	}
	if($pdf_files == 'none'){
		$pdf_files = $_POST[old_pdf_file];
		//echo "::None File::";
	}
	/* Upload pdf file */

	$dateformat = date('dmy',strtotime($_POST['faq_lastupdate']));
	
	$folder = "../../../pdf/";
	$language = $_POST['faq_language'];
	//$filename_pdf_file = time() . '_' . $_FILES[pdf_file]['name'];
	$filename = 'Sanctuary_Club_FAQ_'.$dateformat. '_' . $language. '.pdf';
	$pdf_files = upload_files('pdf_file', $folder, $filename);