I have occasionally read about old passports people collect as keepsakes of their travels. Now, I just came across a mention of “all old passports” in a list of things to bring to a US visa interview so it seems to be a perfectly common and official thing.
That's surprising for me because I always had to hand in my old passport to the consulate to get a new one. I never asked if it was a requirement but while researching this question, I found out that it actually was. Apparently, in France, if you want to renew your passport, you are only allowed to keep the old one if it contains a valid visa and that only for the duration of the visa in question (no idea how they enforce that last restriction, if they do it at all, but officially it seems to be the rule). I also came across many forum posts from people who basically lied about losing their passport to keep it (you have to sign a form to that effect so I wouldn't consider it entirely benign).
Is it common for other countries to let people keep old passports? Do you have to lie about losing the old one, simply ask to keep it or is it perhaps even standard procedure to punch/cut the passport and return it to its holder? Is there any other country where handing in an old passport is in principle required? Are there any international recommendations about that?