worked it out. Added extra code to the extra div. For those who want to know:
style.css
#access_wr {
position: absolute;
top: 170px;
margin: 0 auto;
width: 940px;
}
#access {
position: absolute;
left: 0;
display: block;
float: left;
margin: 0 auto;
width: 470px;
}
#access2 {
position: absolute;
left: 470px;
display: block;
float: left;
margin: 0 auto;
width: 470px;
}
header.php
<div id="access_wr">
<div id="access" role="navigation">
<?php /* Allow screen readers / text browsers to skip the navigation menu and get right to the good stuff */ ?>
<div class="skip-link screen-reader-text"><a href="#content" title="<?php esc_attr_e( 'Skip to content', 'twentyten' ); ?>"><?php _e( 'Skip to content', 'twentyten' ); ?></a></div>
<?php /* Our navigation menu. If one isn't filled out, wp_nav_menu falls back to wp_page_menu. The menu assiged to the primary position is the one used. If none is assigned, the menu with the lowest ID is used. */ ?>
<?php wp_nav_menu( array( 'container_class' => 'menu-header', 'theme_location' => 'primary' ) ); ?>
</div><!-- #access2 -->
<div id="access2" role="navigation">
<?php /* Allow screen readers / text browsers to skip the navigation menu and get right to the good stuff */ ?>
<div class="skip-link screen-reader-text"><a href="#content" title="<?php esc_attr_e( 'Skip to content', 'twentyten' ); ?>"><?php _e( 'Skip to content', 'twentyten' ); ?></a></div>
<?php /* Our navigation menu. If one isn't filled out, wp_nav_menu falls back to wp_page_menu. The menu assiged to the primary position is the one used. If none is assigned, the menu with the lowest ID is used. */ ?>
<?php wp_nav_menu( array( 'container_class' => 'menu-header', 'theme_location' => 'secondary' ) ); ?>
</div><!-- #access2 -->
</div>
functions.php
// This theme uses wp_nav_menu() in one location.
register_nav_menus( array(
'primary' => __( 'Primary Navigation', 'twentyten' ),
'secondary' => __( 'Secondary Navigation', 'twentyten' ),
) );
Thanks katmac!