One would be led to believe a two motor running board would have a motor at the front of the board and a motor at the back of the running board. I would think it would go a long way toward reducing a bind caused by long linkage that would be required with a single motor. Where the motors are located in relation to each other would probably answer a lot of questions, but I would be rather doubtful a two motor unit could function if one motor failed.

Given the OP's location, I would suspect motorized running boards would be a pretty high maintenance item. Probably pretty nice if you don't mind the keep up time and effort.