test.php

<?php
return array(
  "post_type" => array(
    "cpt1",
    "cpt2"
  ),
    'posts_per_page' => 28,
	'orderby' => 'rand',
);
?>



<?php while ( have_posts() ) : the_post(); ?>
    <?php if ( 'cpt1' == $post->post_type ) : ?>
    	Hello World
	<?php endif; ?>
	<?php if ( 'cpt2' == $post->post_type ) : ?>
    	Goodbye World
	<?php endif; ?>
<?php endwhile; ?>