One chap on quora gave me the following answer
I've never seen it work that way. You're basically attempting to run a virtualized environment within a virtualized environment. Logically, it doesn't make much sense. And my guess would be that it either won't work, or will cause a crash as the one is attempting to overwrite hardware interrupts of the other. I know running two VM managers side-by-side on the same host is a recipe for disaster as they keep falling over each other's feet. So my guess would be there are similar issues when running one inside another.
At best it would run a lot slower as two virtual environments work layered one on top of another. At worst the host will crash once the secondary VM starts. But by all means, try it and see if it does in fact work ... isn't that one of the reasons one uses such VMs? To try stuff out?
His answer can be found here
