Trouble with multiple loops and do_not_duplicate

<?php get_header(); ?>

<h1>Loop 1</h1>
<?php $do_not_duplicate = array();
$my_query = new WP_Query(array('posts_per_page' => 1, 'post__not_in' => get_option( 'sticky_posts' ) ) );
while ($my_query->have_posts()) : $my_query->the_post();
$do_not_duplicate[]  = $post->ID; ?>
<h2><a href="<?php the_permalink();?>"><?php the_title();?></a></h2>
<?php endwhile; ?>
<?php wp_reset_query(); ?>


<h1>Loop 2</h1>
<?php
 $args=array(
      'posts_per_page' => 1,
      'post__not_in' => $do_not_duplicate,
      'category__in' => array($category->term_id)
);
$my_query = new WP_Query( $args );
while ($my_query->have_posts()) : $my_query->the_post();
$do_not_duplicate[] = $post->ID; ?>
<h2><a href="<?php the_permalink();?>"><?php the_title();?></a></h2>
<?php endwhile; ?>
<?php wp_reset_query(); ?>

<h1>Loop 3</h1>
<?php $args=array(
      'posts_per_page' => 1,
      'post__not_in' => array_merge($do_not_duplicate, get_option( 'sticky_posts' )),
      'category__in' => array($category->term_id)
);
$my_query = new WP_Query( $args );
while ($my_query->have_posts()) : $my_query->the_post();
$do_not_duplicate[] = $post->ID; ?>
<h2><a href="<?php the_permalink();?>"><?php the_title();?></a></h2>
<?php endwhile; ?>
<?php wp_reset_query(); ?>

<h1>Loop 4 (leftovers)</h1>
<?php if (have_posts()) : while (have_posts()) : the_post();
 if (in_array($post->ID, $do_not_duplicate)) continue;
 ?>
<h2><a href="<?php the_permalink();?>"><?php the_title();?></a></h2>
<?php endwhile; ?>
<?php else: ?>
<?php endif; ?>

<?php get_footer(); ?>