I just received an Announcer badge for this question. As far as I can remember, I've never seen this question before. I certainly haven't shared it (I know nothing about this game, and it looks okay rule/meta wise, so I can't think of any reason why I would have needed to share a link). Yet the badge is in my list of accomplishments.
According to this related meta question, one reason this might occur is due to user error - whoever actually posted a link mistyped my user ID instead of theirs. Though I guess it's possible, none of the users associated with that question (asker, answerers, and commenters) seem to have IDs close to mine, so I don't know if this is the case or not.
As much as I like shiny badges, I don't want to "steal" one from another person if that's what happened. Similarly, if the system glitched out, I don't want to have a cheated badge either.