During the recent upgrade of OTM v6.1.0 to OTM v6.2.1, I discovered that OTM stores IP address of its servers in the following files:
For Apache and Weblogic services, OTM listens on virtual IP of the instance, so there is no port conflict as the Virtual_IP:Port remains unique.
However, the Tomcat component listens on localhost on port 8007 by default. So if you have two OTM instances share the same physical box as application tier, you need to change the default port of 8007 to some other port which is available. This change is made in $GLOG_HOME/tomcat/conf/server.xml.