Board Thread:Wiki-Related Discussion/@comment-929837-20141109085917/@comment-4975807-20141109210241

Ursula is the Sea Witch, I agree, but Regina still masqueraded as her, which is why it's noted on Regina's page that she played the key role of Sea Witch with Ariel. This is to show Regina, not Ursula, bargained with Ariel to keep her legs rather than the real Ursula doing so.