Multiple Loops duplicate post question

Hi

In total I want to display 4 posts in which I created 2 loops where the goal of the first loop is to show the 2 latest posts.
The second loop should display 2 posts random, excluding the first 2 of above. This works fine except for one thing:

Instead of displaying 2 posts the second loop leaves the space empty if it selects one post from the first loop. Who can help me solve this issue?

This is my code:

<div id="vids">
		<?php $my_query = new WP_Query('cat=-3,-6&posts_per_page=2&orderby=date&order=DESC');?>
		<?php while ($my_query->have_posts()) : $my_query->the_post();

 $do_not_duplicate[] = $post->ID ?>

	<div class="homevideo">
	<div class="category">
	<?php the_category(' '); ?>
	</div>
	<div class="videothumb">
	<img src="<?php video_thumbnail(); ?>" width="185" height="105" />
	</div>
	<div class="videoname">
      <a href="<?php the_permalink() ?>" > <?php the_title(); ?>  </a>
    </div>
        </div>
		<?php endwhile; ?>
		<?php $my_newquery = new WP_Query('cat=-3,-6&posts_per_page=2&orderby=rand');?>
<?php while ($my_newquery->have_posts()) : $my_newquery->the_post();

if (in_array($post->ID, $do_not_duplicate)) continue;
 ?>
	<div class="homevideo">
	<div class="category">
	<?php the_category(' '); ?>
	</div>
	<div class="videothumb">
	<img src="<?php video_thumbnail(); ?>" width="185" height="105" />
	</div>
	<div class="videoname">
      <a href="<?php the_permalink() ?>" > <?php the_title(); ?>  </a>
    </div>
        </div>

		 <?php endwhile; ?>
<?php wp_reset_query(); ?>

thanks a lot in advance!

Joost