Networking - Serving multiple instances of a scene.

I'm currenly developing a game with objective to serve roughly 100 players. The idea is that 100 players will be in one scene, and once they collide with one another, they both get put into a different scene. This scene will provide a "duel to the death" kind of thing, and the winner of the death-duel will be ported back into the scene with the other 98 people.

My question really is, how do I put these two players in the SAME scene? There will have to be different instances of this scene for all the different duels. How do I achieve this?

I've thought of the following options:

1. One of the two people whom have collided becomes server of an instance of the duel. The other client connects to this "server", after finishing the winner connects back to the main server. I figured that this 1v1 duel could be locally hosted on one of the machines, where the real server handles all the 100 players.

2. The server keeps a list of all the difference instances of the duel scene, and handles accordingly. I have no clue how to exactly work this out, but this seems like a plausible option.

Any suggestions on how to make this work, or any more design ideas, are very welcome!

Thanks for your time reading this!