Duplicate Menu

case 'duplicate':
        //check_admin_referer( SOMETHING HERE );

        //get selected menu information
        $duplicated_nav_menu_id=$nav_menu_selected_id;
        $duplicated_nav_menu = wp_get_nav_menu_object( $nav_menu_selected_id );
        $duplicated_nav_menu_items = wp_get_nav_menu_items($nav_menu_selected_id);

        //$duplicate_nav_menu = wp_duplicate_nav_menu( $nav_menu_selected_id ); //I'd like to have this as a separate function in nav-menu.php in wp-includes.

        //create new menu name -> borrowed from Add New under Update
        $new_menu_title = $duplicated_nav_menu->name.''.rand();

        $_nav_menu_selected_id = wp_update_nav_menu_object( 0, array('menu-name' => $new_menu_title) ); // 0 means create new menu; 2nd arg is an array of menu data

        if ( is_wp_error( $_nav_menu_selected_id ) ) {
            $messages[] = '<div id="message" class="error"><p>' . $_nav_menu_selected_id->get_error_message() . '</p></div>';
        } else {
            if ( ( $_menu_locations = get_registered_nav_menus() ) && 1 == count( wp_get_nav_menus() ) )
                set_theme_mod( 'nav_menu_locations', array( key( $_menu_locations ) => $_nav_menu_selected_id ) );
            unset( $_menu_locations );
            $_menu_object = wp_get_nav_menu_object( $_nav_menu_selected_id );
            $new_nav_menu_title = $_menu_object->name;

            $_menu_object = wp_get_nav_menu_object( $duplicated_nav_menu_id );
            $nav_menu_selected_title = $_menu_object->name; //duplicated menu name

            $nav_menu_selected_id = $_nav_menu_selected_id; //newly created menu id
            $messages[] = '<div id="message" class="updated"><p>' . sprintf( __('The <strong>%s</strong> menu has been successfully created.'), $new_menu_title ) . '</p></div>';
        }
        //update new menu

        break;

//after delete-action

<div class="duplicate-action">
    <a class="submitduplicate duplication menu-duplicate" href="<?php echo esc_url( wp_nonce_url( admin_url('nav-menus.php?action=duplicate&amp;menu=' . $nav_menu_selected_id), 'duplicate-nav_menu-' . $nav_menu_selected_id ) ); ?>"><?php _e('Duplicate Menu'); ?></a>
</div><!-- END .duplicate-action -->