I'm very tempted to bring the hammer down on the proliferation of tags, but I think that impulse might be misplaced.
To reap the benefits of a folksonomy we really do need to leave it be, focusing attention just on the harmful tags. I don't think redundant tags qualify as harmful: the only poor behaviour it encourages is slapping too many tags on a question, and that's not something that's going to get "out of hand" since it can be fixed whenever. Eventually it will be obvious which tags the community prefers (apart from the harmful ones, which should die by fire before then).
In the meantime: if in doubt, I say leave it be. When it's obvious that there's a better tag, make them synonyms.