Crypt returns the same hash for two different (similar) passwords

I have a problem using crypt () if the user has a password (password1 in this example) and they change it to password2, the hashing returns the same result. You can check it here: OLD LINK Enter password1 as the current password, and password2 as the new password and confirm the password, you will see the results. If you enter a completely different password, no problem. I understand that there are other ways to use hashing passwords, etc. I'm more curious than anything. My code is below:

<?php

$oldpassword="password1";

echo "<form method=\"post\">
<p>Enter Current Password: <input type=\"password\" name=\"currentpassword\" /></p>
<p>Enter New Password: <input type=\"password\" name=\"password\" /></p>
<p>Confirm New Password: <input type=\"password\" name=\"confirmpassword\" /></p>
<p><input type=\"submit\" value=\"Change Password\"></p>
</form>";

$user_id = $_SESSION['user_id'];
$pass=$_POST['password'];
$salt = 'xxxxx';
$currentpassword = crypt($_POST['currentpassword'], $salt);
$oldpassword = crypt($oldpassword, $salt);
if(isset($_POST['password'])) {
    if ($currentpassword !== $oldpassword) {
        echo "The password you entered for current password does not match our records.";
    }
    else {
        if ($_POST['password'] && $_POST['confirmpassword']) {
            if ($_POST['password'] == $_POST['confirmpassword']) {
            $hash = crypt($pass, $salt);
                if ($hash == $currentpassword) {
                    echo "Current Password:&nbsp;";
                    var_dump($_POST['currentpassword']);
                    echo "<br/>";
                    echo "New Password:&nbsp;";
                    var_dump($_POST['password']);
                    echo "<br/>";
                    echo "New Hash:&nbsp";
                    var_dump($hash);
                    echo "<br/>";
                    echo "Current Password Hash:&nbsp";
                    var_dump($currentpassword);
                    echo "<br/>";
                    echo "<hr/>";
                    echo "Your new password cannot be the same as your current password.";
                }
                else {
                    echo "Your password has been changed successfully<br/>";
                }
            } else {
                echo "Your passwords do not match. Please try again.";
            }
        }
    }
}

?>