[Plugin: Theme My login] New user IP

Hi How to check IP with theme-my-login plugin ? I have created theme-my-login-custom.php file and added this code:

<?php
function tml_register_form( &$template ) {
$IP = isset($_SERVER['HTTP_X_FORWARDED_FOR']) ?
$_SERVER['HTTP_X_FORWARDED_FOR'] : $_SERVER['REMOTE_ADDR'];	

echo '<p><input type="hidden" name="my-field" id="my-field' .
$template->the_instance . '" value="' . $IP . '" size="20" />' . "\n";
}
add_action( 'tml_register_form', 'tml_register_form' );

function tml_registration_errors( $errors, $user_login ) {
global $wpdb;
$select_user = "SELECT user_ip FROM v2_users WHERE user_ip =
'".mysql_real_escape_string($IP)."' ";
	$user_ip = $wpdb->get_var(htmlspecialchars($select_user));

if ($_POST['my-field'] == $user_ip){
$errors->add( 'empty_my-field', __( '"You cant have two accounts' ) );
}
}
add_action( 'registration_errors', 'tml_registration_errors', 10, 2 );

function tml_user_register( $user_id ) {
global $wpdb;

$IP = isset($_SERVER['HTTP_X_FORWARDED_FOR']) ?
$_SERVER['HTTP_X_FORWARDED_FOR'] : $_SERVER['REMOTE_ADDR'];	

$data = date("Y-m-d H:i:s");
$data_yst = date("Y-m-d", strtotime("+7 day"));

$wpdb->update('v2_users', array("user_registered" => $data,
"user_demo_date" => $data_yst, "user_ip" => $IP, "user_taller" =>
'1000'), array('id' => $user_id), array( '%s'), array( '%d' ) );
}
	add_action( 'tml_new_user_registered', 'tml_user_register' );

?>

but user will pass with the samwe IP and user can have account as many as he wants