Irssi with psybnc on multiple nets

Hi folks,

I currently use irssi to connect to my shell running psy.  I would
like to have different nicks on different nets.  However, when I
reconnect to my shell, irssi sets all the nicks to whatever is
currently in irssi's %nick variable.

Is there any way to stop irssi from doing this?

Thank you,
Nathan