How to redirect before page processing along with all the sent data?
My suggestion (experimental) is something like this (but NOT RECOMMENDED):

function MY_THEME_preprocess_page(&amp;$variables) {
  if(arg(0) == 'node' &amp;&amp; is_numeric(arg(1))) {
    $nid = arg(1);
    if($nid == '23423') {    
      drupal_goto('node\45644');
    }
  }
}


function MY_THEME_node_view($node, $view_mode, $langcode) {
  if($node-&gt;nid == 45644) {
    $old_node = node_load(23423);
    $old_node_view = node_view($old_node);

    $node-&gt;content['body'] = $old_node_view['body'];
  }
}