Weclock: yeah, the wishlist is totally farked, you should read a few older threads around here, they address this issue at length.
Medieval: Total war and Medieval: Total war viking evasion is an expansion pack to medieval: total war.
I think the main thing that would help is to just have someone at gog, or a volunteer/a couple of people from the forums to go through the wishlist and look at the games and merge them if they should be and then have the database lock the name down and if someone tries to add the game again it points them to it.
Basically like how Gametz has a list of things and the database will check the spelling of it when you submit it and then tell you if it can't find an exact match (IE because you didn't spell it right or something) then it allows you to browse a list of similar named games to see if it is there. If it isn't, then you can put a request to have that game added and someone will check it to make sure if isn't a duplicate and is a legit game and then it'll be added to the database.