Try taking just the name from the page admin link and see if it works. Something like this:
function custom_menu_order($menu_ord) {
if (!$menu_ord) return true;
return array(
'index.php', // Dashboard
'separator1', // First separator
'edit.php', // Posts
'pluginname2', // Take the name from the page menu admin.php?page=pluginname2
'upload.php', // Media
'edit.php?post_type=page', // Pages
'edit-comments.php', // Comments
'pluginname', // Take the name from the page menu admin.php?page=pluginname
);
}
add_filter('custom_menu_order', 'custom_menu_order'); // Activate custom_menu_order
add_filter('menu_order', 'custom_menu_order');