I’m trying to make an aim trainer for me and my friends.

My question is I’m trying to create arenas some private and some public where you can make custom matches with certain rules. But how do servers like UKN and other aim training servers handle arenas? Because when I look at the maps, it seems like everything is sometimes overlaid.

For example, I joined the same map on Rust Reborn Bedwars in two different lobbies, both in the same place, but with different people.

Are they using multiple servers, or are they stacking arenas on top of each other? And if they are stacking them, how can players in different arenas not hear each other? If not what plugins are they using.