I haven't heard the term, walking.
All the off-road trailers bigger than a teardrop are almost always dual.
The trailer can glide thru dips, holes, ditches and over bumps better as one tire drops in and the other maintains ride height, so no drastic side to side bouncing.
Also the trailer does better at angles as there is an axle closer to the rear and an axle closer to the front than if it were single axle. Departure angle is distance from rear tire to that spot on the rear bumper that will hit, so dual axle has a tire farther to the rear. Same for the front.
In soft sand the weight is spread out more too.
Side-loading the tire might pop off a single tire, but again, two tires only see half the side load.
Even on moderate forest service gravel roads you get these benefits, not needed but nice.