What you need to do is RENAME your 1.16 versions, everything included which means all the hidden files where the mods go. It will be located in DOCUMENTS and SETTINGS.
Then you must install the game again, and then search GOOGLE for a 1.05 patch. There are plenty out there, so you should not have a problem.
So in the end you will have two copies, one that is 1.05, and one that is 1.16. This is how I have it on my machine now.