Umm no one mentioned scaling, but utilization, which is something completely different. Both cards at 52% utilization could basically still be 1.5 times as fast as a single GPU, or it could be much lower (say 1.2 times). We simply don't know. So there's not really anything to derive from that number, other than that AMD and Oxide need to work on their software to utilize the hardware better.
The Maths there doesn't work unless crossfire is somehow creating extra power.
I just assumed either 50% scaling or the second card at 50% which may indeed be 50% scaling. I could be wrong though there.