Watching ESB again last night, I had the thought that perhaps the second Wampa was supposed to be a female, and that the male which attacked Luke was elsewhere in that scene. I wonder if that was supposed to be the implication all along, since they had filmed several Wampas attacking Echo base.
Nah it’s not that. There’re interviews out there where they discuss that they filmed the Wampa originally on location, but that the original model got damaged in transit back before they did pickups back in the UK, so they had to rebuild it. It’s intended to be the same Wampa.
Ady’s problem is that if he were to try to imitate the Wampa it’d still be inconsistent with either of the existing ones, so he’s replacing both with one consistent model.