hmhmm - the average user (me included) wouldn’t have a clue which key is the right one
…this would mean a horrible amout of keys every day for me … of course it is not really a problem … but I would rather see hostile take-overs (maybe with 24/48h delay - or simply a message popping up “the owner of this domain has changed within the last 2 days”)
For me just a network notification sounds perfectly fine … everybody knows it’s not the same site as before and therefore would be cautious … and then the original user can decide if he just wants to move to another address or try to win it back