During the beta period, Microsoft called the next version of Visual Studio simply "Visual Studio 11." The tag visual-studio-11 was created.
It's now reached Release Candidate status, and they've decided to go back to their yearly theme by calling the product "Visual Studio 2012." visual-studio-2012 has now come into existence.
The two are effectively the same product, but there are significant changes between Beta and RC. Should the tags be merged, or should they remain separate?