Displaying different featured post in category template

Hi everyone,
Here is my problem. I have 5 different categories, displayed in a category template (category.php), with a color by category. I would like to display 1 featured post, for each category. (using the tag “featured”, but if you have a better idea…)
example :
“baby” have 1 featured post
“mom” have 1 featured post
…

I use this code (found here)

<?php

global $wp_query;
$args = array_merge( $wp_query->query, array( 'post__not_in' => $do_not_duplicate ) );
query_posts( $args );

    $args = array(
            'posts_per_page' => 1,
            'tag' => 'featured',
        );

        $featured = new WP_Query($args);
        if($featured->have_posts()): while($featured->have_posts()): $featured->the_post();
            the_title();

        endwhile; else:

        endif;
    ?>

I have the same featured post displayed in all categories. How to display each featured post in their current category ?
Thanks in advance !