I wasn't suggesting he should double--although, unlike Ritz, he rarely gets hurt--only that there was a rather notable American who had done so, and successfully at that. Also, the schedule in London is easier than it was for Shorter (a poster earlier in this thread provided the schedule below):
Aug. 4 evening - 10,000 final
Aug. 8 morning - 5,000 heats
Aug. 11 evening - 5,000 final
Aug. 12 11:00 AM - Marathon