You will need one $ONCONFIG file per server,
In these ONCONFIG files you have to make sure your ROOTPATH points to different devices. Same for the DBSERVERNUM. you need different numbers for the two servers.
In these servers you create your database.
You will have a 'common' sqlhosts' file; Probably containing two lines per server, one shm, and one tcp. you will need two lines in your /etc/services file. You need to configure two ports, on efor each server.