<?php
    $wp_query_authors = new WP_User_Query( array( 'fields' => 'all_with_meta' ) );
    $authors = $wp_query_authors->get_results();
    foreach($authors as $author) :
            $favorites = wpfp_get_users_favorites($author);
            if (is_array($favorites)) :
                if (in_array($post->ID, wpfp_get_users_favorites($author))) :
                    echo $author->display_name . '<br/>';
                endif;
            else:
                echo "not array";
            endif;
    endforeach;
?>