That's because the artists got lazy and just recolored a two mouth darkruler. Would've been better if they actually made a dragon that resembled the original fusion material.
Aww, don't 🔥 my dragon... He's awesome in Forbidden Memories. It's not his fault that his 3D model, like that of most other monsters, was terrible in that game!
Twin thunder dragon fusion was staple in Forbidden Memories for new players. Epic card, could be equipped with everything. Have to admit the 3D model made it look like an alien.