Originally Posted by robert@honda
Instead of a 90-degree offset, stacking the blades on top of each other will allow them to make two cuts in any grass blade, pine straw, etc. that's sticking up. This will make the cut material two smaller pieces vs. one large piece, which means it will disperse move evenly or fill a grass bag more completely.
All but a couple of Honda models use twin-blades this way, and the cut quality is excellent.
Caveat: I work for Honda, but the preceding is my opinion alone.
I thought about that but could not figure a way to do it without lowering the bottom blade. The honda mowers that use this system have everything machine fitted. I am going to try the quadracut top blade with an extreme high lift oem blade in springtime. As you can see in the pic, the honda blade sits perfectly across the 2 1/2" factory high lift. It was then simply a matter of putting in a washer reducing the hole from 1 1/4" to 1/2". In the spring/summer I am not as worried about pulverizing leaves and grass because I side discharge. I am more hoping this setup leads to a crisper cut with less stringers.