I believe TWINS was incrporated into both Girafarig's and Wobbuffet's design. It's as if they decided to axe the idea of it evolving into Girafarig, but then realized they can "keep it alive" by incorporating some of its traits to both Girafarig and Wobbuffet (hell, maybe it even turned into Wobbuffet throughout various redesigns). This would explain why we have 2 vastly different mons next to each other that somehow share a similar trait: a "conscious" tail-head with eyes.