Yes, when I installed the 2012 RC, it screwed up my install of 2010. I had to repair the install. Grrr. Same thing happened when I installed the RTM (double dutch grr), but that may be because I had previously installed the RC on the same machine.
Other than that, they both run well side by side.
If your actions inspire others to dream more, learn more, do more and become more, you are a leader.-John Q. Adams You must accept one of two basic premises: Either we are alone in the universe, or we are not alone in the universe. And either way, the implications are staggering.-Wernher von Braun Only two things are infinite, the universe and human stupidity, and I'm not sure about the former.-Albert Einstein