Razor blades: new vs. refills?

So in the midst of relocating I’d managed misplace my razor, which is probably somewhere in Kansas on a moving truck right now. Just as I was getting my act together to get a new one, I heard Adam Curry mention the new vibrating “m3 power” razor on DSC. “What the heck, I’ll give it a shot”. The light touch and vibration took some getting used to, but I liked the end result. It felt great. Then I thought, given the importance of that first shave in selling refills (presumably where most of the earnings are made), the razor companies might have some incentive to ship better blades with the razor. The moment passed and would have passed forever if one of Adam’s listeners hadn’t raised the same theory.

Upshot, I took a closer look, and noticed that the blade that shipped with the razor was ever so slightly different from the refill. Here is a picture of a marking on the back of a new blade:

C 17 marking on the back of the blade that shipped with my new m3 power razor

And here is a picture of the same place on a refill blade:

AE 3 marking on the back of the blade that shipped with my new m3 power razor

What could it mean?