I just found an interesting variation of one of the purple granite type Caesars Emperors Club cards from the Caesars Palace Casino in Las Vegas. Specifically, the next to last light purple card in the 3rd issue where the phone numbers are aligned on the back and the card only has a mag stripe. On the originally listed card the bottom line on the reverse is 73mm wide and on this newly found card it's 74mm wide. In fact, every line of text on the back is about 1mm wider than the currently listed card. It's stands out when the cards are next to each other, otherwise you probably wouldn't notice.
Here's a scan of the newly found card so you can see which card I'm talking about, you'll notice the text starts very close to the left edge