1. We would’ve met Jekyll and Hyde during the episode but never see them on screen together. The “heroes” bring Jekyll to Storybrooke where it is revealed in the last scene that he and Hyde are one and the same and he transform between the two (kind of like Glory in Buffy)
2. The “heroes” bring Jekyll but turns out Jekyll is the bad one and Hyde is the good one.
3. Jekyll and Hyde play their traditional good/evil roles but turn up to Storybrooke separately. One with Rumple, one with the “heroes”