JSPWIKI-830: Prettify breaks when using on the same page#

https://issues.apache.org/jira/browse/JSPWIKI-830

Validating page.

<?xml version="1.0" encoding="UTF-8"?>
<val>
  <prop att="audience" val="foo" action="include"/>
  <prop att="audience" val="bar" action="exclude"/>
</val>
Other stuff