[caramelcard]

Hi Ralph,

We've talked a bit about it over the years here so you could search the board for old threads if it's helpful.

Although collector stamps are common like "Gilliam Squires" which is found on a lot of Obaks, these are not collector stamps. The purple number stamps are period and were applied at the factory. Maybe for sorting. Maybe for inspection before leaving. Not sure really, but they're common and found on other Bay Area issues that probably used the same lithographer.

Some appear to be weird shapes, but I think it's the same numbers that were stamped too fast over stamped over another number.

Maybe other folks have concrete evidence of why they were stamped...

Rob