I would to like to know if you guys could answer this question to me. I want to know if I can have two machines (one real and another a virtual machine being hosted on the real machine) with the same external IP address without conflicting.

To keep things simple, machine1 = Real Server and machine2 = Virtual Windows Server. I use machine1 to host my email, ftp, web server, and dns. I like to play a game called cubeworld which only works on windows computers. So, I made a virtual machine that ran windows and called it machine2. machine1 has already some ports opened on the router to the external IP 10 (10 is just an example). I want to know if I can open some ports on machine2 while routing to the same external IP, 10 that machine1 has ports routed to. Is this possible? Will a conflict occur? Is there anyway to do this via the DNS or something?

Thanks.

So far as I know, the same address cannot exist on two machines in the same subnet.

Exactly what I was thinking yet there are a few friends of mine saying otherwise, not exactly the opposite but they have machines with the same external IP which I believe is possible. So I would basically require another external IP port in order to do what I want yes?

You can have your virtual machine NATed via the host, and then you wouldn't need to alter the port-forwards on the router, but you would need to set up another set of port-forwards on your host to translate the traffic to your VM.

Much easier really to bridge the VM so it gets it's own IP on your LAN and point the forwards for the game to it from your router.