Since at this moment very few users have the sufficient reputations to even propose tag synonyms, and duplicate tags are already starting to be a problem, this is going to be a place for any member to point out which tag should be redirected where.
Post the redirections as answers, with any number of proposed redirections organized as a list. Entries shall be of the format:
Add new ones as they come to the bottom of your lists. If we get too many answers and it becomes hard to track new propositions, once in a while myself or anyone with an edit questions privilege can add all new entries to the list at the end of this question.
Note to whomever will actually edit the tags: after you do, please edit the entries in the corresponding post which proposed the change to indicate which ones had been changed.
List of proposed changes: