Magento1 Adding Extra WYSIWYG editor to Magento admin CMS Page Content Section

[ocAsanka]

I need to add extra WYSIWYG editor in CMS > Pages > Content section. See below,

It has added through observer, In config.xml

<adminhtml_cms_page_edit_tab_content_prepare_form>
            <observers>
                <abcrewrite_page_edit_tab_content>
                    <type>singleton</type>
                    <class>Abc_Pqr_Model_Observer</class>
                    <method>setCmsPageSummary</method>
                </abcrewrite_page_edit_tab_content>
            </observers>
</adminhtml_cms_page_edit_tab_content_prepare_form>

In my observer.php

public function setCmsPageSummary($observer)
{    $cmsPage = Mage::registry('cms_page');    $form    = $observer->getForm();    $fieldset =  $form->getElement('content_fieldset');    $fieldset->addField('cms_page_summary', 'editor', array(
         'name'    => 'cms_page_summary',
         'label'   => Mage::helper('cms')->__('Cms Page Summary'),
         'title'   => Mage::helper('cms')->__('Cms Page Summary'),
         'config'  => Mage::getSingleton('cms/wysiwyg_config')->getConfig(                 array('add_variables'            => false,
                       'add_widgets'              => false,
                       'files_browser_window_url' => Mage::getSingleton(
                               'adminhtml/url'
                           )->getUrl('adminhtml/cms_wysiwyg_images/index'))
             ),
         'wysiwyg'    => true,
         'value'      => $cmsPage->getCmsPageSummary(),
         'disabled'   => false,
    ));
}

The problem was when I try to insert image to content section, the image url is past on 'cms page summary' section which I newly added one. but It should past inside content editor not in newly added editor.

Same thing happen magento default, I just checked in magento-ce 1.9 duplicate the core field in app/code/core/Mage/Adminhtml/Block/Cms/Page/Edit/Tab/Content.php 

$contentField = $fieldset->addField('content1', 'editor', array(
            'name'      => 'content1',
            'style'     => 'height:36em;',
            'required'  => true,
            'disabled'  => $isElementDisabled,
            'config'    => $wysiwygConfig
        ));

How do I avoid this issue???