NOTE: People are pointing out that the replay number is 21 the first time but 20 the second time, THERE IS NO SWITCH. I had deleted an old replay that I didn't want anymore, check the time and date of the two replays, they're the same: 3/23/2008 12:10
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PwnagePanda posted a thread at NSider2 regarding a replay of his that 'broke'. One time the fight would play normally as it happened, the next time, it would mess up and there would be a totally different outcome (Which including him SDing once)
I recreated the stage and tested it myself, the results of that test are in the video :P