I'm just guessing, so I'm probably wrong, but I would imagine the cards are not numbered ahead of time, and they are not numbered by the players. Once the player signs them, and the company gets them back, the company probably goes through them and numbers them, setting aside any damaged and/or more nicely done ones. I wouldn't think they would want to take chances with the players numbering them.
I'm just guessing, so I'm probably wrong, but I would imagine the cards are not numbered ahead of time, and they are not numbered by the players. Once the player signs them, and the company gets them back, the company probably goes through them and numbers them, setting aside any damaged and/or more nicely done ones. I wouldn't think they would want to take chances with the players numbering them.
I have actually read in another thread on here a while ago that they are numbered by the manufacturers.
There are cards where they are consiered "buy backs", they are hand numbered but not autographed, thus not handled by the player. I have pulled a couple of these from fleer products. Here is one for example;