You can run two servers without problem. They need to named differently, ie: "Server" and "Server1". Still best to have the servers with static IP addresses, ie: 192.168.0.1 (Server) and 192.168.0.2 (Server1). Your client machines will not be able to join both servers (for backup), but should be able to access either.
I ran two servers for a short period. No issues on the network.
P.S. The server names and addresses are for info purposes only, you can name them anything you want and assign whatever addresses you or your network has.
I also have 2 servers running together on the same network and have them on the same workgroup as my workstations. With the same ids on both, you can create icons on your pc desktops that connect to both shared folders, and connect net use connections as you wish. The only problem I had was getting them to both work remotely. I finally gave up and connect externally with my HP and use the server I call my beta server on the lan only. One server can be completely configured with the firewall ports, then the second needs the ports redefined, but the 4125 can't be changed, so streaming is out of the question. You can get close by redefining the second server with alternate ports for 80 and 443, and then getting to the second machine by using the https://servername.homeserver.comecondportid where servername directs you to your external IP address. I also had a problem redefining the second WebGuide port, so with those problems I gave up.
I hope this makes sense to you.
Good luck and let us know if you get further than I.