Multiple sitemaps in one masterpage in Asp.net

<siteMap defaultProvider="MainMapProvider" enabled="true" >
<providers>
<clear /> <!-- get rid of the inherited standard provider -->
<add name="MainMapProvider" description="The Main Map"
type="System.Web.XmlSiteMapProvider"
siteMapFile="mainmap.sitemap" />
<add name="FooterMapProvider" description="The Main Map"
type="System.Web.XmlSiteMapProvider"
siteMapFile="footer.sitemap" />
</siteMap>