"If a story has had significant attention in the last year or so, we kill reposts as duplicates. If not, a small number of reposts is ok." https://news.ycombinator.com/newsfaq.html

If you repost an older story I'd recommend adding the relevant year to the title, e.g. "Do Things That Don’t Scale (2013)" https://news.ycombinator.com/item?id=14957007