CUBE CE

I am thinking of updating to CE. Not entirely sure if it is better than 6.4. However, I want to be able to access both 6.4 and CE to make comparisons and see if this is something I want to do right now given I have projects that are ongoing. Is it possible to have my license in both 6.4 and CE or does activating the CE license deactivates the 6.4 license.