My friend recently told me that he went to a Richter concert in 1975 in London that he had played an insane Beethoven Hammy, but somehow is not satisfied with the result (even though they gave him standing ovation)
and played the fugue for the encore
is there a recording exist for such occasion? 
Yes. I have it too. 
Yeah, it’s on the Stradivarius label. Long out of print. I can post it for you if you’d like.
It’s my least favourite of the 6 Richter Hammerklaviers I have, though it’s still a fine performance.
The best commercial rec is IMO the BBC Legends disc Hammerklavier from Aldeburgh 1975. The Prague one is excellent as well.
o, my friend was raving about it, but he doesn’t have the recording
i would appreciate ifu would post the disc for me
I think Kreso ul’ed it.
hmm… I don’t think so… I don’t think I have this rec; I hope somebody other will upload it!
ok. Someone uled it and I downloaded it 
I believe Honza posted a radio broadcast of the entire recital - some of which was not commercially released.
Only the Hammerklavier is on CD - minus the encore of the 4th mov. I’ll post the CD, since I don’t like to repost other peoples’ uploads.
Tiz da RECTUM n u no it. We muz rezzerect da tru zpeech of diz cuntry.
ebay is selling this cd now for $10.
It was a common practice for Richter. He used to say the Hammy was impossible to play one-shot. He felt the obligation to replay the last mvt as an encore, to get it right.
I wonder if Chris has full stats about that. How many times did he play the last mvt as an encore in his career?