The multiplex page.tpl.php contains the following hardcoded lines, which are the same for all pages:

    <meta name="description" content="Your description goes here" />
    <meta name="keywords" content="your,keywords,come,here" />

It's better to define those lines in the page level since they are different for each page. This is done best by the nodewords module.

Please remove those lines from the code.