Suggest we merge utf8 into the correct tag utf-8, and make former a synonym of utf-8.
Maybe there's a more general fix you could make in the StackExchange code - when creating a new tag, save the canonical version of the tag (all hyphens stripped) in a new column. Then when creating another new tag, check its canonical version to see if it matches any existing canonical version. This would prevent new tags that only vary from other tags by adding or subtracting hyphens.