I'm not sure why you would want to do this other than 2 AIO's, but yes, if you have the radiators configured in such a way that they are on the left or right and not straight up. That was badly explained but if you look for toms latest dual xeon build, you'll see that he has 2 H75's in the roof of his 760t (I can't remember the case, sorry)
If someone else could find it and link it for you that would be great but I'm too tired tonight.