It's not only been allowed for a few months, dang has mentioned that there's also some semi-automated reposting. There is also a 'past' link under titles now, that will show you links that the system thinks are reposts (e.g. there have been at least 4 submissions for this actual page, but the system also thinks an article, "CEOs are often the last to know" is the same? - https://hn.algolia.com/?query=The%20Panic%20Sign&sort=byDate...)