Following on [this](https://judaism.meta.stackexchange.com/q/2080/440) question, what should the policy be if an existing question with an existing answer gets a new answer that is higher quality (e.g. provides a source, maybe adds additional information, but leaves the original answer with nothing new or distinct about it)?

Should the new content be merged into the old answer? Should the old answer be deleted in favor of the new one? תיקו (let it stand)?