I just went to badges page and noticed the a badge was awarded to a person twice in a short notice. So i just checked those questions and found the votes on that answer is exactly the votes required to get the badge.
I checked the 'Voting Corrected' FAQ and its related to a user who either upvote or downvote another users answers/question will get adjusted.
So my concern is if a user could create 5 to 10 accounts and use a primary account to answer and other accounts to just vote up the answers and/or questions, how SFSE system would detect that?