Hi,
Yes, you can do what you have in mind with just one public ip address.
That is why you need to specify different ports from the public interface,
to point to different private/internal ip address.
E.g you would connect from the internet using mstsc /v:x.x.x.x:1111,
that would connect you to server A, then using mstsc /v:x.x.x.x:1112,
you should be connected to the second server.
HTH
-Viconsul