Can I do a dual VOR check on the ground?
Be careful performing a dual VOR check on the ground, especially if you are located near other aircraft or buildings that may interfere with the signal.  I have performed a VOR check on the ground at a few airports around the Southwest, and I have found that you can get erroneous readings, on the ground, compared to performing the dual check in the air. I would say its more accurate in the air.
As for how to log it. DATE, PLACE, ERROR, and SIGNATURE. Place, meaning the VOR station identifier. 91.171(d)