Afaik, installing a beta will overwrite the version you already have. So unless you have a partition, or you can install on a second machine, it will probably overwrite your stable version.
Having said that, you could install the beta, and make a copy of your project before opening it. That way you've always got the original to revert to if there are any problems. And if you don't like the new beta, you can just roll back to an older, more stable version.
Hope that helped.