Tapestry doesn't clear page values, even if they are not persistent?

If I add a list to a page, even if the list is not persistent, its values are persisted on the page, and are shown even to different users and session (they are in the global)

Steps to reproduce:
biuld an app with the start page and start tml attached.

1) invoke the start page with no parameter on the activation context (eg, simply calling "start")
the page will show "empty"

2) invoke the start page with some parameter (eg, calling "start/a/b")
the page will show "filled"

3) from now on, the page will no more show "empty", even if invoked with no parameters

Regards,
larzeni