[radhakr]

The virtual worlds already exist, all you need to do is put someone in it. Just make "/duel1" like a normal teleport command but add SetPlayerVirtualWorld(playerid, worldid) in to it, where worldid is the number of the virtual world you would like to use (it can be anything from 1 to 2,147,483,647, but for simplicity's sake you should probably just use 1). When a player spawns the player's virtual world is set back to the default, 0.