Stable and current on same harddrive?

[Michael]

When 4.6 is released, I'll be upgrading my system to it. 
I am curious if it is possible to run 4.6 and current on the same harddrive?
I would like to play with current for learning. I thought I read somewhere about doing that, but can't find the info. I've searched Marc, the faq, daemonforums, but can't find it. Maybe I'm using the wrong words in my search? 

Thanks


-- 
"Estimated amount of glucose used by an adult human brain each day, 
expressed in M&Ms: 250"


  - Harper's Index