It doesn't have any kind of simple option for creating a secondary server out of an existing one, or of transferring clients between servers within the GUI. However, you can manually install a second server instance and use that to manage some of the clients if you want, since GSS is licensed on a per-client, not a per-server basis.
As long as you have licenses for the clients, you can install more server instances. Normally, the way it works is that a fresh server install will generate a fresh identifying certificate (the privkey.crt file) and matching public identifier (the pubkey.crt) which the clients use to bind to the specific server instance they are associated with.
Right now, clients only bind to a single server, and stick with that one (we could change that, but it's not something a lot of people have asked for).