Dude, you’re doing this the hard way. You can do what you want totally with a single ‘featured post thumbnail’. Read the documentation about thumbnail sizes in themes. You can inject custom thumbnail sizes in your themes funcitons.php and then give them as a parameter to the (get_)the_post_thumbnail() function. Please just read the documentation at the Codex – start with the function reference page for the_post_thumbnail(), maybe – and you’ll see. WordPress does automatically resize and crop the image for you, if only you tell it to do so.
