Whether or not you can do this depends a lot on the capbabilities of your DSL router. I assume you are using NAT on the router to translate internal IP addresses on your 2 computers to an external IP address that is assigned to the router. This would be the IP address that your ISP has assigned, either statically or via DHCP when the router is turned on. On some routers you can do port forwarding, where a connection coming in on a particular port is forwarded to a particular machine. For instance, you forward connections on port 110 to an email server, and connections on port 80 to a web server. In your case if the router will do port forwarding, forward different ports for remote access to each of your computers. Then assuming RAdmin (I haven’t used it so don’t know) will allow you to designate what port to connect to, you can use the port designation to connect to the computer you want to, while leaving the IP address the same.
Best – Doug