Crosswalk Polygon Design Choice

I was looking at the semantic layers of the crosswalks and noticed that sometimes you have two polygons representing one crosswalk, and the two polygons will often overlap. Just wondering what the significance of this is and the design choice. Thanks!

Hi. I never noticed that, but looking at your figure it seems as if that may be a design choice? The two parts seems to align neatly with the lanes in the two directions.