Multi-core KingsRow tested

I have been testing KingsRow 1.16d against Cake 1.8x12 on my quadcore machine. Here are some results of engine matches at 5 seconds per move:

Cake 1.8x12 - KingsRow 1.16d (1 core)  +19 -14 =255
Cake 1.8x12 - KingsRow 1.16d (2 cores) +19 -18 =251
Cake 1.8x12 - KingsRow 1.16d (4 cores) +18 -19 =251

I had been expecting Cake to be slaughtered by the multi-core version of KingsRow, but apparently it's not that bad. To check whether or not it might be a bug in the multithreaded search of KingsRow, I played a match with Cake and KingsRow running on 1 core, but KingsRow got 10 seconds per move - so essentially this should reproduce the second match above. I found

Cake 1.8x12 - KingsRow 1.16d (10s)  +17 -21 =250

There is always some variability in engine matches, otherwise one might conclude that the 2-core version of KingsRow was not performing as well as KingsRow with twice the search time. As it is, I don't quite know what to make of it.