Hi it isn't a good idea to post multiple threads click here
If your question isn't answered, respond to it yourself with "bump" or "help me please" or whatever to bring it to the top of the board.
I can't see any reason why you can't install more than one version. During installation, specify a different folder for the game to go in. I could nvisage this causing confusion unless you rename desktop shortcuts so it is obvious which one is which.