Do you mean two trailers at one event, or two reveals in a single trailer?
If it's two reveals in a single trailer, I don't know how likely that is - the only times that I can think of where we've had those (Robin and Lucina, technically Palutena and Dark Pit, Simon and Richter, Ken and Incineroar), an Echo fighter was involved. Unless we're getting a bonus echo fighter as part of one of the challenger packs (like, for example, Crash and Coco, where they fight the same but Coco has different hitboxes so she can't be an alternate costume), I don't think that will happen.