Minecraft 1.8

[Jonathan Meer]

No, the reference to the nether was an analogy to the way the connectivity with the old world would work. There's nothing there that indicates the old world overwrote the nether. Likely, some small mod was written for it (either by a community member, or by the guy himself that allowed for the creation of portals that 'teleport' an individual, like a nether portal does. Then, just figure out how to get the 'old world' to register as a destination just as the nether registers as a potential destination, and hey presto; no need for two servers.