<?php
global $post;
$categories = get_the_category();
$category = $categories[0];
$sidebar_cat_id = $category->cat_ID;
$sidebar_cat_name = $category->cat_name;
?>
<?php
$sidebar_related_query = new WP_Query('cat=' . $sidebar_cat_id . '&showposts=5&offset=0&orderby=post_date&order=desc');
while ($sidebar_related_query->have_posts()) : $sidebar_related_query->the_post();
$do_not_duplicate = $post->ID;
?>
<li>
<h3><a href="<?php the_permalink(); ?>"><?php the_title(); ?></a> <br /> <span><?php the_time('d.m.Y'); ?></span></h3>
</li>
<?php endwhile; ?>
</ul>
