What does keycode punched mean?

I just received a "brand new" CD from one of the sellers on Amazon and the keycode is punched out on the back. Why is this done?

Merry Christmas to all, Dolfan
It's called a "cut-out". They also used to do the same with vinyl LP's. It's a way that record companies discount overstocked CD's. By intentionally "damaging" the product, it becomes a factory second, and can therefore be discounted. The CD or LP is, of course, perfect; it's just the packaging that's "damaged".

That the basics, as I understand it. Perhaps others know more details.
Fatparrot is exactly right.

I would also add that sometimes companies will put a hole through the bar code (or mark it in some way so that it can't scan) if it is a promo cd. So, you can expect that it is either a promo copy or a cut-out. The cd will be perfect.