My votes:
One-day double: Nurmi, Paris 1924, 1500m/5000m
One-day multi: Jesse Owens, May 25, 1935: set three WRs and tied another, all within 45 minutes: equaled 100y WR (9.4), broke LJ WR (26'8¼", stood for 25 years), broke 220y WR (20.3), broke 220y hurdles WR (22.6).
One-meet double (not triple): Juantorena, Montreal 1976: 400m/800m
One-meet multi (tie):
Zatopek, Helsinki 1952: 5000m/10,000m/marathon
Fanny Blankers-Koen, London 1948: 4 golds--100m, 80m hurdles, 200m (largest-ever margin of victory in OG 200), 4x100m (came from 3rd to win on anchor). Competed in 11 heats/finals in 8 days. (Held HJ and LJ WRs but was limited by rules to 3 individual events.)
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I guess no one's going to talk about Junxia Wang in 1993. (I know, but people also have doubts about Lewis, Johnson, Bolt, Juantorena, Viren, El G, and probably everyone else who'd make this list post-Zatopek.)
Sept. 9: Unofficially broke 5000m and 3000m WRs in the last 5000m and 3000m of her 29:31.78 10,000m (a WR by :42 and still :22 ahead of next-best ever, 18 years later)
Sept. 11: Broke 1500m WR with 3:51.92 but lost to Qu; still #4 all-time
Sept. 12: Broke 3000m WR by :09 with 8:12.19 in semifinal
Sept. 13: Broke 3000m WR by another :06 with 8:06:11 (still WR by same amount)
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Others worth considering:
Marie-Jose Perec in Atlanta 1996 (beat Johnson to the Olympic 200/400 double)
Mary Decker in Helsinki 1983 (3000m/1500m gold, beat fresh trio of dubious Russians in second race while probably clean herself at the time)