Magento Duplicate Header Fix

Http.php

<?php 

/** 
 * 
 * Place this file at app/code/local/Mage/Core/Controller/Response/Http.php
 *
 */

/**
 * Magento
 *
 * NOTICE OF LICENSE
 *
 * This source file is subject to the Open Software License (OSL 3.0)
 * that is bundled with this package in the file LICENSE.txt.
 * It is also available through the world-wide-web at this URL:
 * http://opensource.org/licenses/osl-3.0.php
 * If you did not receive a copy of the license and are unable to
 * obtain it through the world-wide-web, please send an email
 * to license@magentocommerce.com so we can send you a copy immediately.
 *
 * DISCLAIMER
 *
 * Do not edit or add to this file if you wish to upgrade Magento to newer
 * versions in the future. If you wish to customize Magento for your
 * needs please refer to http://www.magentocommerce.com for more information.
 *
 * @category    Mage
 * @package     Mage_Core
 * @copyright   Copyright (c) 2012 Magento Inc. (http://www.magentocommerce.com)
 * @license     http://opensource.org/licenses/osl-3.0.php  Open Software License (OSL 3.0)
 */


/**
 * Custom Zend_Controller_Response_Http class (formally)
 *
 * @author      Magento Core Team <core@magentocommerce.com>
 */
class Mage_Core_Controller_Response_Http extends Zend_Controller_Response_Http
{
    /**
     * Transport object for observers to perform
     *
     * @var Varien_Object
     */
    protected static $_transportObject = null;

    /**
     * Fixes CGI only one Status header allowed bug
     *
     * @link  http://bugs.php.net/bug.php?id=36705
     *
     * @return Mage_Core_Controller_Response_Http
     */
    public function sendHeaders()
    {
        if (!$this->canSendHeaders()) {
            Mage::log('HEADERS ALREADY SENT: '.mageDebugBacktrace(true, true, true));
            return $this;
        }

        if (substr(php_sapi_name(), 0, 3) == 'fpm') {
            $statusSent  = FALSE;
            // REWRITE START
            $contentSent = FALSE;
            // REWRITE END
            foreach ($this->_headersRaw as $i=>$header) {
                if (stripos($header, 'status:')===0 || stripos($header, 'http/1.1')===0) {
                    if ($statusSent) {
                        unset($this->_headersRaw[$i]);
                    } else {
                        $statusSent = true;
                    }
                }
                // REWRITE START
                if (stripos($header, 'content-type')===0) {
                    if ($contentSent) {
                        unset($this->_headersRaw[$i]);
                    } else {
                        $contentSent = true;
                    }
                }
                // REWRITE END
            }
            foreach ($this->_headers as $i=>$header) {
                if (strcasecmp($header['name'], 'status')===0 || strcasecmp($header['name'], 'Http/1.1')===0) {
                    if ($statusSent) {
                        unset($this->_headers[$i]);
                    } else {
                        $statusSent = true;
                    }
                }
                // REWRITE START
                if (strcasecmp($header['name'], 'content-type')===0) {
                    if ($contentSent) {
                        unset($this->_headers[$i]);
                    } else {
                        $contentSent = true;
                    }
                }
                // REWRITE END
            }
        }
        parent::sendHeaders();
    }

    public function sendResponse()
    {
        Mage::dispatchEvent('http_response_send_before', array('response'=>$this));
        return parent::sendResponse();
    }

    /**
     * Additionally check for session messages in several domains case
     *
     * @param string $url
     * @param int $code
     * @return Mage_Core_Controller_Response_Http
     */
    public function setRedirect($url, $code = 302)
    {
        /**
         * Use single transport object instance
         */
        if (self::$_transportObject === null) {
            self::$_transportObject = new Varien_Object;
        }
        self::$_transportObject->setUrl($url);
        self::$_transportObject->setCode($code);
        Mage::dispatchEvent('controller_response_redirect',
                array('response' => $this, 'transport' => self::$_transportObject));

        return parent::setRedirect(self::$_transportObject->getUrl(), self::$_transportObject->getCode());
    }
}