Have only seen stamp on early (flat plug) type oil coolers and separate stamps as i think someone who made a copy made them together as if they were made separately ford could keep using the 2 coats epoxy over and only keep changing the date stamp and the only documented date stamps i seen were 68 date.
Could be correct in that it was likely the same worker that applied both stamps and maybe he or another worker assigned to the tasked sometimes got them both lined up nicely together and other times not even close.
Agree that some did make and sell (maybe still does) a single stamp with both aligned nicely. The picture of that stamp I have is dated Feb 20 1969. Guessing like some makers of stamps he might not have gone to the effort of producing a bunch of different dates for his stamps plus it would allow him to track when his stamps were used and applied. I've done that just to see how many people someone that got one of my stamps and how many friend he or she shared them with. Making little changed other changes will produce the same tracking ability also.
It is sort of interesting that I have pictures of what was represented as a NOS cooler that was stamped with a neat Two Coats and date with a Feb 26 1969 date.
Also have a particle from a 69 GT500 example with only a small amount of the stamp left. Can't figure out how the letters (what I can make out) fit into either of the two stamps. Maybe I'm just looking past the answer
Ed - Thanks for sharing