If you are talking about Diablo II than yes. The way to do it is to copy your whole game folder, name the copy as something else, than when you install the patch it will only be on the one that is named normally.
I did this so I could play patch v.1.09d and 1.11 at the same time. <img src="/ubbthreads/images/graemlins/winkwink.gif" alt="" />
If you need more details (I dont think theres much more tho) just say so.
Killerzzz
