if you need your app to run in the same context for two virtual hosts,
you could try creating one host element in your config and use an alias
element. As using two host elements will run your application in
different contexts
for example:

<Host name="virtualHost1" ...>
 <Alias>virtualHost2</Alias>
</Host>

(see
http://tomcat.apache.org/tomcat-5.5-doc/config/host.html#Host%20Name%20Aliases)

worth a go, never tested it.

Tim