I initially thought it might have had one of those LEFT SIDED blades where the cutting edge is to the Left, not RIGHT side of the blade mistakenly installed. Yes, they have them for machines that may rotate the blade in the other direction. Oregon has them.

Rusty,I had a man bring me a mower, shiny practically new mower, one time, claimed it didn't cut. It started first pull, ran perfect, but sure enough, just wouldn't cut hot butter. I tilted it up, and lo and behold, yep....blade was on upside down. I showed it to the customer, and he said, and I kid you not..."I put it on that way so it would cut better when I pull it backwards". I had a heck of a time not laughing at him as I explained that the engine direction did not change when you pulled the mower backwards!!! I just turned the blade over and sent him on his way...lol gotta love the general public!