Twin System Question

I am having two operating systems running on the same machine.

 

Now I am planning to get NIS 2009 licence copy.

 

So can I install NIS on both O.S ?

 

Will it give any activation error as one of the systems will be having it installed before the other O.S.

 

In short can I install NIS 2009 on two systems of same machine with the same price?