If I get your question right, then the answer is that there is no real
idea of a Username and Password that is made available to your
application.
The authentication is handled by the Google AppEngine framework and
then an authentication user is redirected to your page.
You would then choose to validate your user dependent content by
querying a db.UserProperty element. Various examples should how you
can get access to a current user.
Above all you should not have to worry about passwords etc.
Also generally if a server is using a port number the second sever
should fail to start. I am not sure why dev_appserver starts two
processes listening on the same port number.
--
"I never look back darling, it distracts from the now", Edna Mode (The
Incredibles)