Steppings change on AMD Athlon 64s

According to the site, the steppings changed from C0 to CG, but both sets of chips are being sold in the same shops, requiring people to be careful which one they're getting.

The site has pictures of the different chips, demonstrating what the problem is.

The chips appear to operate at different clock speeds, which is puzzling. Can AMD be preparing for a shift to Intel numbers? We don't think so somehow. At least not yet.

One operates at 2000MHz, and another at 2200MHz, but they've both something in common. They are marked at 3200+, it appears.

As you can see, here.