The chip pictured has an even weaker hotstamp on the reverse side.

The chip I have in my personal collection is almost new and the hotstamp looks similar to this chip. I honestly think there was a problem with the machine when these were made. As you can see, the left side of the chip has the HS dug deep. Then it gets shallower (and weaker) as it moves to the right. Seems consistant with the 4 or 5 I have seen.

In fact....if you look here and look at all the PANS, they have similar characteristics
http://www.themogh.org/cg_chip2.php?id=NVLVFO