There are many browsers out there and they all have their own behavior when you open a new window. For me Firefox opens a new window with nothing in it (probably because I have no home page set). Internet Explorer opens a new window with the same page from the previous window open. However, it opens the page from the cache if it can it would seem.
The only way you'll be able to enforce this "always load" behavior is to explicitly set an immediate expiration for the page so the browser is forced to re-request the page every time it loads it. However this will have the side effect of also reloading the page if the user hits the browser back/forward button and goes views your page again.