They could do that, and I totally get that something like that happened hehe. It's much harder for someone to do that and more noticeable and out in the open. In that scenario you can downvote those people when found out.

What to do in a 50/50 situation? Downvote the people that are getting upvoted who are just making posts? That becomes a bad situation because then dozens or hundreds of innocent people get caught up in the downvoting, vs the person with their sockpuppet accounts getting downvoted.