网格布局在magento

我已经在我的模块中创建了一个自定义选项卡并成功显示一个网格输出，但我的问题是我们如何在一个页面中显示两个网格序列化块?我已经尝试用这个代码调用两个序列化块。

public function customgridAction()
{
   $this->loadLayout();
    $this->getLayout()->getBlock('regionpage.productgrid')->setProductsGrid($this->getRequest()->getPost('products_grid', null));
    $this->getLayout()->getBlock('regionpage.articlegrid')->setArticlesGrid($this->getRequest()->getPost('articles_grid', null));
    $this->renderLayout();
}

这就是我的布局xml的样子

<regionpage_adminhtml_regionpage_customgrid>
<block type="core/text_list" name="root">
    <block type="regionpage/adminhtml_regionpage_edit_tab_productgrid" name="regionpage.productgrid"/>
    <block type="adminhtml/widget_grid_serializer" name="regionpage_productgrid">
        <reference name="regionpage_productgrid">
            <action method="initSerializerBlock">
                <grid_block_name>regionpage.productgrid</grid_block_name>
                <data_callback>getSelectedProducts</data_callback>
                <hidden_input_name>links[productgrid]</hidden_input_name>
                <reload_param_name>products_grid</reload_param_name>
            </action>
            <action method="addColumnInputName">
                <input_name>position</input_name>
            </action>
        </reference>
    </block>
</block>

 <regionpage_adminhtml_regionpage_customgrid>
    <block type="core/text_list" name="root">
        <block type="regionpage/adminhtml_regionpage_edit_tab_articlegrid" name="regionpage.articlegrid"/>
        <block type="adminhtml/widget_grid_serializer" name="regionpage_articlegrid">
            <reference name="regionpage_articlegrid">
                <action method="initSerializerBlock">
                    <grid_block_name>regionpage.articlegrid</grid_block_name>
                    <data_callback>getSelectedArticles</data_callback>
                    <hidden_input_name>links[articlegrid]</hidden_input_name>
                    <reload_param_name>articles_grid</reload_param_name>
                </action>
                <action method="addColumnInputName">
                    <input_name>position</input_name>
                </action>
            </reference>
        </block>
    </block>
 </regionpage_adminhtml_regionpage_customgrid>

但是它输出最后一个块，而不是两个块。