RA2 Yuri: Have wsock32.dll & 2 valid copies of C&C Ultimate. Cannot join LAN games

I have two copies of C&C Ultimate. One on my sons system and one on mine.

We are attempting to play Yuris Revenge across our lan.

One system running Win 7 64 bit.

One running Win 7 32 bit.

In order to get around the IPX issue I downloaded wsocks32.dll into both of our C&C RA2 directories.

We can now see one another in the Lobby of a Network game, but when we attempt to join a game hosted by the other of the two systems we get the error message "There is already a player with your serial# in that game."

I have check the registry and the serial numbers for our respective games are present and distinct from one another (each matching that of their own game case).