I don't know which you'll want to keep, but they're definitely synonyms.
5
Done. I kept humor over humour because the first was used 6 times, while the latter was only used once.
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1I'm not on english.sx a lot, so I don't know what policies on American vs. British spelling usually are here, but it seems appropriate to use only one of them for tags and have the other be synonyms. – doncherry Aug 30 '11 at 0:06