According to this Reddit Discussion there's a single owner trying to be a candidate for multiple block producer spots. I know this has something to do with transparency, but I'd like to read an answer from an expert.
The main worry of a single owner running multiple candidacies for multiple BP spots is related to a centralization of the network.
While there is no technical way to "ban" a misbehaving candidate, community currently highlights those who are under the suspicion in Telegram chats, community forums, reddit and other mediums. If proven right, candidates risk losing their reputation.
Indeed, processes around transparency will help in minimizing risks of a single entity running/investing into multiple BPs.