400m 1st or 100m 1st

excellent question and a recent post stated Joel Milburn from Aus ran a 200m PB 20 or 30 (can’t recall which) after a 400m. While not at any decent level I ran a SB 200m less than 20 mins (still breathing hard on line) after a 400m.

There is also the matter of Marita Koch running a 300m 60 or so mins prior to her 400m WR.