I'm just assuming that the viewpoint switches sides at that point, but that's a confusing choice to make. Perhaps the artist thought they were following the 180 rule by keeping each character to the same side of the frame, but in this case that would be a bad interpretation of the rule. Here the entire premise requires that they walk past each other, so the viewer expects them to switch sides of the frame and is disoriented when they didn't. Or maybe the artist actually intended that they nonsensically switch directions after bumping each other? I suppose we can only guess.