Custom Plugin -> theme filter

I am creating custom plugin and in my plugin file I have this:

add_filter('page_template', 'load_tq_templates');
function load_tq_templates() {
    if (is_page( 'transport-quote-1' )) {
         if ( $overridden_template = locate_template( 'tq-1.php' ) ) {
           // locate_template() returns path to file
           // if either the child theme or the parent theme have overridden the template
           load_template( $overridden_template );
         } else {
           // If neither the child nor parent theme have overridden the template,
           // we load the template from the 'templates' sub-directory of the directory this file is in
           load_template( dirname( __FILE__ ) . '/templates/tq-1.php' );
         }
    }

I’ve created sub-folder “themes” in my plugin directory where I have file tq-1.php looking like this:

<?php get_header(); ?>
<div class="wrapper">
       <h1>THIS IS MY CUSTOM THEME FOR PAGE tq-1</h1>
    <div id="content">
               <?php if (have_posts()) : while (have_posts()) : the_post(); ?>
               <?php the_content(); ?>
               <?php endwhile; endif; ?>
    </div>
</div>
<?php get_footer(); ?>

Problem is that the file really get’s loaded on appropriate page, BUT after it’s loaded the active theme’s PAGE.PHP is loaded as well, so I am basically getting duplicated content on front end as tq-1.php is loaded first and then theme’s page.php file is loaded second.

How to avoid theme’s page.php from being loaded after my template?

What I am doing wrong ?