It's was the same (+14) when I tried it point blank, off F3, and off 4 with both clones in both stances. That is about the extent I care to test it since I barely use Stunt Double
-------
The method I used was doing a cancel into Mimic Summon, recording how negative that is on block, and using that to determine the cancel advantage, per say.
Some examples:
4 xx Mimic Summon = -11
4 SKRC = +23
F3 xx Mimic Summon =-17
F3 SKRC = +17
Using some baseline SKRC data I had gathered and verified, I now can easily figure out any of the SKRC block data by using Mimic Summon.