INSERT INTO ของผมมัน double ใน SQL INSERT INTO ของผมมัน double 2 record ใน SQL ครับ

<?php
//$con = mysql_connect("host","user","password");

include "connect.php";

$datetime=date("Y-m-d H:i:s");
$ipaddress = $_SERVER['REMOTE_ADDR']; //Get user IP
$browser = $_SERVER['HTTP_USER_AGENT']; //Get user browser

echo $datetime;
echo $ipaddress;
echo $browser;

mysql_select_db("fwdmember", $con);
$sql="INSERT INTO tblcontact (Title,Firstname,Lastname,Email,Phone,Enquiry,datetime,ipaddress,browser)
VALUES ('$_POST[Title]','$_POST[Firstname]','$_POST[Lastname]','$_POST[Email]','$_POST[Phone]','$_POST[Enquiry]','$datetime','$ipaddress','$browser')";

mysql_query($sql); 
$id = mysql_insert_id(); 
$id_string = "FWD".str_pad($id, 4, "0", STR_PAD_LEFT);
echo $id_string;

if (!mysql_query($sql,$con))
  {
  die('Error: ' . mysql_error());
  }
echo "Thank you for your submit";

mysql_close($con)
?>