There is already a player with the same serrial#

Me and my friend bought and paid for the Command & Conquer the Ultimate collection, and when we try to play Red Alert 2 Yuri's Revenge there is an error.

We are able to find each other in the network lobby, but when we try to join each other game, a massege pops op that says "Ther is already a player with the same serrial# "  So we are not able to play toghetter. But when we try to join some one ellses game, then there is no problem.

I hope you under stand what the trubol is so that we can fix it and start to play. 

It seems like there are many trubols in Origin, so I hope you can help us with this silly problem!

Thank you!