You can run multiple nodes for a chain on the same server, if you use the datadir runtime parameter to separate the directories for each one. For this trial we recommend you use version 2.2.1 beta 1 (available at the bottom of the download page) which has improved management of node connections.
Here's a further node from the development team about this:
A MultiChain node will try to connect to all nodes seen before - local or remote. In the case of local, it will try to connect to all ports it knows. But if it is already connected to some external IP, it will not try to connect to another node on the same IP. So, in the case of, say, 100 nodes on 10 IPs, it is likely that all nodes on the same IP will be interconnected and each of them will be connected to a single node on another IP.
This should still be good enough to test the performance.