This sounds very familiar to what my husband gets and he does not have ON. It's usually something that happens when he is in a situation where there is a lot of things going on around him like a crowded restaurant, lots of people talking, moving etc. His neuro explained it to us as a brain overload issue where there is too much info to process at once and it effects vision. Besides the double vision if its really bad and we don't get him out of the area quickly the room starts spinning as well. Most of the time just getting him to a quiet area helps. Also have tried earplugs, and that seemed to delay it a bit longer.