[Zope] Multiple Browser Id Managers question

Hi Zope List, The current SESSION Chapter in the Zope Book 2.7 says the following: " ... once you've instantiated one browser id manager or if you keep the default browser id manager, you will not be able to instantiate another browser id manager in a place where the new browser id manager can acquire the original browser id manager via its containment path" But I find that I *can* add additional Browser Id Managers in folders that can acquire the original browser id manager - without deleting the default copy in Zope root. Any thought ideas on this? Does the principal still stand, e.g. "Not good to put a browser id manager in a place that can also acquire another browser id manager? Thanks, David