[mod_python] Sessions performance and some numbers

I am going to show my ignorance of how sessions are internally 
implemented
here, but what happens if you happened to have two distinct instances of
Apache running on the same machine? Ie., not one instance of Apache 
listening
on two ports, but two instances each listening on their own ports.

What I am getting at here is that will both instances of Apache if using
mod_python, use the same "mp_sess.dbm" file in "/tmp". Is the way that
information is stored in the database about sessions mean that each 
instance
of Apache sees a different set of session information, or because it is 
the
same database, the session information is effectively shared between the
two and thus a user could login to a session through one instance of
Apache and pick up that session automatically through the other.

Note I am not talking here about prefork and multiple Apache sub 
processes,
I am talking about multiple instances of Apache as a whole.

I haven't looked at the FileSession code yet, but what would it do in 
this
case.

Anyway, I know that in practice this may be rarely done, but just 
curious.

Graham