Same post content, different URLS

I’ve run into a problem. I’ve created a theme that has two different single.php layouts. So i have single1.php and single2.php. The default single.php file looks like this:

<?php
  $post = $wp_query->post;
     if ( in_category('69') || in_category('70') ) {
        include(TEMPLATEPATH . '/single-artist.php');
     } else {
        include(TEMPLATEPATH . '/single-review.php');
     }
?>

This seems to work in terms of displaying differnt post layouts depending on which category the post comes from (which is what I want). The problem I have is, that no matter what post link i click on, the post content is the same, even though the urls are different. Does that make sense? So https://www.blog.com/post1, https://www.blog.com/post2, https://www.blog.com/post3 all display the same content even though their urls are different and the post content should also be different.

Anyone have any ideas as to how I could fix this?