I don't think the Dad's were hand stamped. They look like they were printed on the sheets before cutting.
Same with the Pittsburgh Post-Gazette backs.
They're interesting adaptations of a card issue to an advertising purpose, I suspect with the cooperation of ESCO in the printing and cutting process. Or like these Nu-Card variations on the common western stars cards:
The arcade back shown above is more like the Page's Pittsburgh Milk back stamp on the Homogenized Bond Bread cards, strictly an after-market affair. Nice and interesting and collectible, but with a difference.
