That surprises me Mr Happy. I haven't seen the source code though and my understanding of sessions, if that is what is used, is poor. Assuming it is not the same link pointed to from both servers, both chats by my way of thinking will be separate processes. I'd guess session or otherwise, we are looking at a cookie, perhaps both servers do read the same cookie. Or perhaps my ideas are just wrong.

I'd not looked at this type of chat until recently and am still learning... They look good in terms of compatibility as there is no dependance on things like Java Applets but they seem to involve a lot of browser refreshes and I'd guess work for the http server.