The only time the I have seen a duplicate stamp on the same mold and same color is this chip.

The only difference is that(on the cards....I don’t have both chips) one has $1.00 on the back and the other has the same J in wreaths.
Those are the only 2 chips that are “about “ identical in the records. They were sent to 2 different places. They didn’t duplicate anything.

Could be the same stamp on different molds.
Could be a chip color difference.
Could be a denomination difference.
A font difference.
Inserts were different.
Many varieties.

If you had a blue B & S chip...it would most likely be on the ChipGuide already. (By you). There is a B & S large crown chip.

It doesn’t really matter. The B & S will most likely stay contributed to San Diego.(I’m not ruling out that they never made it there....just unlikely)

Like these chips....there is a note saying that they were sent to Oakland per records Yet they are still listed in San Diego

*** image from ChipGuide

Could these chips have been used in San Diego...of course....but they were sent to Oakland in 1954 and 1957.

I think about shredding these records every day. It’s a curse. I hate having all this info in front of me....telling it.....and always being doubted. There is always an excuse.
Many of these places where too old for any of us to have visited. To have played cards at a place in 1970.... you would need to be about 70 years old today. 1960...80 years old. And have to remember what the chips looked like.