Query multiple meta key values for template

No idea why you’re using clunky custom SQL, use a meta query instead.

$pageposts = get_posts(
    array(
        'posts_per_page' => -1,
        'post_type'      => 'page',
        'post_status'    => 'publish',
        'meta_query'     => array(
            array(
                'key'   => '_wp_page_template',
                'value' => array(
                    'templates/front-page-excerpt.php',
                    'templates/front-page.php',
                )
            )       
        ),  
    )
);