two dovecot instances

Hello, I am currently trying to setup two invocations of dovecot to run on a debian based server. One for director and the other a stock debian instance. The issue I am having is when I go to start the director instance, I receive multiple errors telling me that the listening ports are already in use. I have change these ports in the 10-master.conf file but am still presented with the same errors when starting the second instance. Is this the only file in which the ports need to be changed (10-master.conf) or is there another file in which the ports need to be set?