@mchill saidI've heard of it, and I've heard Short pronounced a fool for believing he really was playing Fischer and not Fritz.
I hope this isn't a repost, but In 2000 Nigel Short lost 8 straight online blitz games against Bobby Fischer (so he claims) This at a time Short was one of the best blitz players in the world. A youtube link on one of these is below.
I've never heard of this. Has anyone else?
https://www.youtube.com/watch?v=7B9p2PrsKWY
Fischer denied it but what aroused Short's curiosity was he asked the player,
who was not claiming to be Fischer if he knew Armando Acevedo (do you?)
Apparently the answer was instant. 'Siegen 1970' and nothing more.
Short then reasoned he was playing and getting beat by Fischer.
(Fischer played Armano Acevedo in the 1970 Olympiad.)
Later someone claimed Short's opponents moves match up with a computer.
So a computer jockey with a knowledge of chess history is the best we can get.
Fischer denying it may have been because then everyone would look at his handle,
then his games and he may have a few awful games in there. Blitz can produce some horrors.