Makwala also did a 44.80 and 20.38 double at La Chaux-de-Fonds this year, on 2 July (not much compared to his other two, but good enough to make note of).
The same day 200/400 is very rare ... so no one else comes to mind even with your sub-45, sub-20.5 criteria.
And I probably shouldn't bother replying to calculo, but all I meant by "fluke" in my original post was a performance I thought might end up being an outlier this year for Makwala; not that it was suspect or somehow a fake/inaccurate time.
I just hope this year he doesn't run a completely unnecessary fast time in the semis at Worlds. He has a history of not delivering at big meets. 2014 Commonwealth games: comes in with a 44.01 and doesn't even make the finals (3rd in his semi in 45.57). 2015 World Champs: comes in with a 43.72, 5th in the final in 44.63.
Last year his best was 44.85 in early June, so he was off all year really (injured at one point I think?) He barely made the semis in Rio (slowest Q time) then was last in his semifinal heat.
I believe he is scheduled for the 400 in Monaco next. Van Niekerk will be in that one too.