I thought I had heard that Mokah is a 50/50 blend of Jahva and Choklat, though I cannot verify that.
In brewing a clone I personally may rely on some chocolate extract in addition to the bittersweet Belgian. With as chocolaty as Choklat is, I am honestly surprised that they do not use extract. I talked with the brewer at a local brew pub recently regarding their chocolate beer. They use extract as that is the best way to ensure consistency in flavor. Maybe brew with the chocolate and add extract at bottling as needed? Either way it is a tasty beer, good luck.