No, it's not the order the pages where created.
for pagination to work properly, the search criteria are stored in a session. For this page, the session is:
$_SESSION["WADbSearch2_email_Results"]
the code i gave you just uses a querystring var to trigger unsetting that session:
if(isset($_GET['show']) && $_GET['show'] == "all") {
unset($_SESSION["WADbSearch2_email_Results"]);
}