[kanzenryu2]

I remember reading about a serious tournament game where somebody castled twice. Nobody noticed during the game. I wonder how many computer databases allow that game to be entered.

[Someone]

That must have been Heidenfeld - Kerins, Dublin 1973.

https://www.chessgames.com/perl/chessgame?gid=2024861.

White castled short on move 10 and long on move 33. That didn’t help, though. White lost the game.

Also, it seems that site’s software doesn’t allow entering the full game.