I see you took the “dull” requirement literally.

I bet having the blades on in the wrong orientation put a ton more wear on your belt, and you were probably burning more fuel than necessary too.

Really? Are you not able to install yours upside down? If you do that then the sharpened edge will be on the trailing side. The mower blades I’ve used would be very obvious that they are upside down, but it is doable.

Of course