This rule is the subject of much debate in league bowling. Say you throw a seven on the left lane, but you should've been bowling on the right lane. Must you have your spare leave duplicated on the correct lane, then attempt your spare there? Or are you penalized for bowling on the wrong lane, giving you a score of zero?
Neither. Once you catch your mistake, your seven is erased. You then take your turn on the correct lane, without penalty, as if your error never occurred. The same rule applies if you and your opponent both bowl on the incorrect lanes. The scores are erased and you start the frame over on the correct lanes.