Avoid duplicates on a view based on results from another view
In the contextual filters, there's an option called «Allow multiple values» just above «Exclude». That option lets you return multiple values separated by commas (and) or mores (or).

So, I just use this code in the «Provide default value» field:

$my_view_name = 'videos';
$my_display_name = 'otros_importantes';

$my_view = views_get_view_result($my_view_name, $my_display_name);
if ( $my_view!=null ) {
  foreach($my_view as $view_row){
    $nodos[]=$view_row-&gt;nid;
  }
}

if(isset($nodos)){
  return implode(",",$nodos);
}
else{
  return 0;
}


And that's all, the nodes shown on that display are ignored.