Styling Select box with jQuery in WordPress

Question

Just trying to style a select box on a WordPress project with jQuery using this plugin.

http://plugins.jquery.com/project/stylish-select-box/

jQuery(document).ready(function(){
    // select box styles
    jQuery('#genre-dropdown').sSelect(); 
});

When I call it on the select box it displays two copies of .newListSelected (the stylable list) instead of one. Below is the code used to produce the select box.

        <?php 

            $args = array(
                'taxonomy'          => 'genre',
                'id'                => 'genre-dropdown',
            );

            wp_dropdown_categories( $args );

         ?>

I've tried with no argument for the custom taxonomy and on a totally different page with the same results.