Often questions have more than one correct answer, and sometimes the answer with the most votes is not selected as the right answer. Sometimes is because the most-voted answer was submitted later. Yet this responses have more comprehensive, complete and up to date answers to the original question. Thus why they are the most-voted answers.
How about, once this scenario happens, the owner of the question is notified or requested by the owner of the most-voted answer to reconsider the correct answer to the question?