That's my point. I looked for false positives or any feature that would distinguish these accounts, and there was none to be found.  The unpleasant situation is that we had a user with a history of exactly this sort of problem with a set of circumstances, reported by users in good standing, that exactly matched sock puppetry.  I had to make a difficult judgment call per all the available information, and the conclusion was a finding of sock puppetry. I have invited checkusers, and others, to review the report.  Everything is available for inspection and comment.  Talk