cannot redeclare JAdminSubMenu

I am getting this error when I try to get into my database.

Fatal error: Cannot redeclare class JAdminSubMenu in /home/carlisle/public_html/administrator/modules/mod_submenu/mod_submenu.php on line 32

I don't know more about PHP an was hoping someone could help me - I administer a joomla site and in time will learn php. I only see a semicolon where line 32 ia. I've read a bit and saw require_once and include_once lines that can make the code only happen once but am not sure if this appile to my file below.

I am getting code twice for JAdminSubmenu on my site.

code:

<?php
/**
* @version $Id:mod_menu.php 2463 2006-02-18 06:05:38Z webImagery $
* @package Joomla
* @copyright Copyright (C) 2005 - 2008 Open Source Matters. All rights reserved.
* See COPYRIGHT.php for copyright notices and details.
*/

// no direct access
defined('_JEXEC') or die('Restricted access');

// Lets get some variables we will need to render the menu
$lang =& JFactory::getLanguage();
$doc =& JFactory::getDocument();
$user =& JFactory::getUser();

// If hidemainmenu is true, we don't want to render this module at all
echo JAdminSubMenu::get();

/**
* Admin Submenu
*
* @package Joomla
* @since 1.5
*/
class JAdminSubMenu
{ (charlie here - this is where line 32 is)
function get()
{
global $mainframe;

// Lets get some variables we are going to need
$menu = JToolBar::getInstance('submenu');
$list = $menu->_bar;
if(!is_array($list) || !count($list))
{
$option = JRequest::getCmd('option');
if($option == 'com_categories')
{
$section = JRequest::getCmd('section');
if ($section) {
if ($section != 'content') {
// special handling for specific core components
$map['com_contact_details'] = 'com_contact';
$map['com_banner'] = 'com_banners';

$option = isset( $map[$section] ) ? $map[$section] : $section;
}
}
}
$list = JAdminSubMenu::_loadDBList($option);
}

if (!is_array($list) || !count($list)) {
return null;
}

$hide = JRequest::getInt('hidemainmenu');
$txt = "<ul id=\"submenu\">\n";

/*
* Iterate through the link items for building the menu items

*/
foreach ($list as $item)
{
$txt .= "<li>\n";
if ($hide)
{
if (isset ($item[2]) && $item[2] == 1) {
$txt .= "<span class=\"nolink active\">".$item[0]."</span>\n";
}
else {
$txt .= "<span class=\"nolink\">".$item[0]."</span>\n";
}
}
else
{
if (isset ($item[2]) && $item[2] == 1) {
$txt .= "<a class=\"active\" href=\"".JFilterOutput::ampReplace($item[1])."\">".$item[0]."</a>\n";
}
else {
$txt .= "<a href=\"".JFilterOutput::ampReplace($item[1])."\">".$item[0]."</a>\n";
}
}
$txt .= "</li>\n";
}

$txt .= "</ul>\n";

return $txt;
}

function _loadDBList( $componentOption )
{
$db =& JFactory::getDBO();
$lang =& JFactory::getLanguage();

$lang->load($componentOption.'.menu');

$query = 'SELECT a.name, a.admin_menu_link, a.admin_menu_img' .
' FROM #__components AS a' .
' INNER JOIN #__components AS b ON b.id = a.parent' .
' WHERE b.option = ' . $db->Quote( $componentOption ) .
' AND b.parent = 0'.
' ORDER BY a.ordering ASC';

$db->setQuery($query);
$items = $db->loadObjectList();

// Process the items
$subMenuList = array();

foreach ($items as $item)
{
if (trim($item->admin_menu_link))
{
// handling for active sub menu item
$active = 0;
if (strpos( @$_SERVER['QUERY_STRING'], $item->admin_menu_link ) !== false ) {
$active = 1;
}

$key = $componentOption.'.'.$item->name;
$subMenuItem[0] = $lang->hasKey($key) ? JText::_($key) : $item->name;
$subMenuItem[1] = 'index.php?'. $item->admin_menu_link;
$subMenuItem[2] = $active;

$subMenuList[] = $subMenuItem;
}
}

return $subMenuList;
}
}