Connecting two separate PCs to host a network

I'm a veteran Spigot and BungeeCord user but have minimal information on networking. I'm trying to figure out how server hosting providers connect two separate machines to run 1 BungeeCord network. I currently am home hosting a network and am looking to buy 2 servers from ebay but would like to know if its possible to link them so i can have 2 Spigot servers on each machine, but 1 BungeeCord server to link all of them up.

Any help would be appreciated.

Thanks,
Sloth