If your intention is to ban or otherwise try to restrict that user, then that's difficult. For example, it could be a guest IP refreshing, or bots (assuming you serve ads to guests, and not just logged-in users). You can't really take action against a guest, unless you manually IP ban a guest, and even then it doesn't do much here (they could do it again with a different IP, or it could be bots).
Honestly, this is something your ad vendor should really figure out and deal with on their side. It's a bit more difficult to do on your side using an add-on.