<?php
    // session_start();
    $_SESSION["pages"] = array();
    
    $i = 0;
    while (true)
    {
        if (empty($_SESSION["pages"]))
        {
            echo "resetting array\n";
            $_SESSION["pages"] = range(0, 7);
        }

        $page = mt_rand(0, count($_SESSION["pages"])-1);
        echo "Page = $page, {$_SESSION["pages"][$page]}\n";
        array_splice($_SESSION["pages"], $page, 1);

        if ($i > 22)
            break;

        $i++;
    }
?>

resetting array
Page = 6, 6
Page = 4, 4
Page = 1, 1
Page = 0, 0
Page = 3, 7
Page = 1, 3
Page = 1, 5
Page = 0, 2
resetting array
Page = 4, 4
Page = 3, 3
Page = 0, 0
Page = 3, 6
Page = 3, 7
Page = 0, 1
Page = 1, 5
Page = 0, 2
resetting array
Page = 3, 3
Page = 4, 5
Page = 2, 2
Page = 2, 4
Page = 1, 1
Page = 1, 6
Page = 1, 7
Page = 0, 0