"My interpretation of the repeated scenes is that the entire movie was a flashback -- the beating did not actually happen twice, it's just that in the end we finally put the event in context."

I wondered if we were supposed to think that too, but it doesn't add up: he does different things when he wakes up at the academic's flat at the end of the movie to at the start of the movie – he doesn't play one of his old records, he doesn't make himself scrambled eggs – and, most notably, he doesn't let the cat escape!