Ann,
It's possible to run multiple OACS "instances" on a single "installation" of Naviserver.
Nevertheless, you must have one file per instance, respectively.
Furthermore, you have broken your statement about the setup being the same, when you confirmed that they have the database to differeante themselves, not mentioning their IP addresses and ports, which must be different as well.
After you create one config file per each instance, you will need to start every instances accordingly.
Ex.
/usr/local/ns/bin/nsd -t /usr/local/ns/config-instance1.tcl -u projop -g nsadmin
/usr/local/ns/bin/nsd -t /usr/local/ns/config-instance2.tcl -u projop -g nsadmin
...
Now, if your goal is to make one single instance of OACS, having multiples sites, then you must look at side-node-map, within /acs-admin section. It will help you accomplish it.
Did I answered your questions?
Best wishes,
I
