title: Order Random without duplicates on pages
body: <p>It's possible make loop with random without duplicate entries?</p>
  
  <p>This is my code, but in page 2, repeat posts of page 1.</p>
  
  <pre><code>&lt;?php global $query_string;
  
  query_posts( $query_string . '&amp;orderby=rand' ); ?&gt;
  
  &lt;?php while(have_posts()): the_post(); ?&gt;
  
      &lt;div id="post-&lt;?php the_ID(); ?&gt;" &lt;?php post_class(); ?&gt;&gt;
  
              &lt;div class="post-content"&gt;
  </code></pre>