The install will overwrite V4.1, so unless you have creature creator (like me) it isn't necessary, OR unless you have V 4.1 sitting in alternate runtimes, then you'll likely have to uninstall one of them to prevent conflicts.

Again however there are a few people who do have both running, there's got to be more than a couple of folks around here who'd like to know what they did to avoid problems. Personally, I really don't need the second v 4.1, but other people do.