Well it's simple, when I try to install the Chinese WoW it shows up an error message, wich includes come patch numbers like 5.0.0 and 5.0.4. Then it auto-closes the installation.

I wonder if this eror shows up becuase of I got another World of Warcraft Installation already at patch 5.0.4 (In other language).

So the question is: Can I have those 2 WoW's at the same time? If it's possible, how?

Yes it's possible. With the 4.0 version all you had to do was uninstall the game in windows control panel and when it asked if you wanted to delete the files you had to answer no.

Or you move the wow folder to another place in your disk and then uninstall to wipe it from windows registry.

Sounds like an error I was getting. I backed up my CWOW and fiddled with the US/CN/zhCN stuff and it managed to update. For the longest time I had two clients (4.0) and it was never a problem as they were in different directories with different names. Just back every build up and change the files suggested in the tech thread.