Reload Problem, user tend to submit data twice

[eluser]worchyld[/eluser]
A unique token does not solve this problem. Every time you submit the form the unique token is always the same!

Code:

<?php
/* This code is not intended to be used on a live site */
session_start();

$unique_code = md5(microtime());

if (empty($_POST)) {
    $_SESSION['unique_code'] = $unique_code;
}

print "POSTED: <br />";
print_r($_POST);
print '<br /><br />SESSION: <br />';
print_r($_SESSION);
?&gt;

&lt;form name="testForm" method="post" action="&lt;?=$_SERVER['PHP_SELF'];?&gt;"&gt;

<p>
    &lt;input type="text" name="name" id="name" value="" /&gt;<br />
    &lt;input type="text" name="unique_code" id="unique_code" value="&lt;?=$unique_code;?&gt;" /&gt;
</p>

<p>
    &lt;input type="submit" /&gt;
</p>

&lt;/form&gt;