My Octane2 has a VBOB connected with two black LVDS cables. The VBOB is recognized by a well known application and flashing a new firmware worked without a problem.
I did not had any chance to use HD-SDI, so I can't say for sure that the whole data path works with two black cables as it is intended to do … but at least your're unlikely to fry your VBOB or DM2/3 by using two black cables.