Ideally, this should be reported immediately after the draw, while there is still an opportunity to randomly change the pairings, but now it is unclear what to do.
Let's do this: if we find a pair that hasn't played yet and is willing to switch opponents, I will change the draw. As a bonus, they will have the opportunity to choose a color/hero without any negotiation.
If we can't find such a pair, then I will replace both of them.