Twin ram will only be more stable at full extension, and not by much at that. At all other points it will make no difference. In fact, I would think the extra bracing you need for a single ram will make the body stiffer and so more stable.Stability at full extension in wind or tipping on a slope is the biggy.
Twin ram trailers are generally more stable ...... IMO of course
If stability on slopes while tipping is an issue then I've seen trailers with a set of rams that clamp down onto the axles and make them rigid.