Having a common login server and 2 gameservers. Also 3 databases for them. Something like that...
loginserver.properties
AcceptNewGameServer = True
URL = jdbc:mysql://localhost/l2jls
server.properties #1
GameserverPort = 7777
URL = jdbc:mysql://localhost/l2jgs_one
server.properties #2
GameserverPort = 7778
URL = jdbc:mysql://localhost/l2jgs_two