If you ever need to add more than one Piwik tracker per page, that is not a problem. You can do it and load piwik.js one time as it helps speed up page loading time. This works because each call to Piwik.getTracker will return a unique tracker object. It works even if each Piwik tracker is pointing at a different server. Here is an example of this in action:
<script type="text/javascript">
var protoCol = ('https:' == document.location.protocol ? 'https://' : 'http://');
document.write(unescape("%3Cscript src='" + protoCol + "URL_1/piwik.js' type='text/javascript'%3E%3C/script%3E"));
</script><script type="text/javascript">
try {
var piwikTracker1 = Piwik.getTracker(protoCol + URL_1/piwik.php", 1);
piwikTracker1.trackPageView();
var piwikTracker2 = Piwik.getTracker(protoCol + URL_2/piwik.php", 4);
piwikTracker2.trackPageView();
} catch( err ) {}
</script>This time the first part of the script only creates a protoCol variable instead of a complete...