I'm by no means and expert at this. I just documented what I did in my specific situation - and that included moving servers. So I can't guarantee that my steps will completely work for you, however there is no reason you shouldn't be able to have two installations of moodle. You would need to make sure your moodledata is named different, your database is named different and your config files reflect the correct paths. If you are on the old 1.9 versions like I was, a major consideration to be aware of before you ever start this process is to make sure you can upgrade your server environment to the specs required for 2.4, otherwise this long process will be a waste and you won't get very far - that's why I had to switch hosting providers and the reason for the "server switch".
by Shawn LoPorto.