R9295x2 Crossfire with r9290x?

I can't find any examples of it, but it should be possible since you can crossfire a 290X with a 290 and the 295X2 is just two OC'd 290X's on a single board. I have no idea what kind of performance that would get you though.
 
Ah okay thanks for the responses. I have an r9295x2 in my computer right now which I just recently got to replace my r9290. I was debating throwing in the 290 to test it out but I am worried about damaging the computer. Plus I only have 1000 watts psu, I think I would probably need 1200 to be on the safe side with that config anyway.