The dies that I described were in a kit, stored in a wooden box and all assigned to inspector "135". As a result, all of them in all the different sizes were Eagle/WaA135 dies.
While it's possible that they were hidden in a sewer for a period of time, neither the box nor the dies deteriorated there. The dies in the box look like new without any corrosion.
Here's what the plate with sample die stamps attached to the top of the wooden box looks like:
(Note that the image is intentionally distorted to make it useless to fakers making new dies... - I posted this to illustrate the variety of dies in the kit.)
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Igitur si vis pacem, para bellum -
- Therefore if you want peace, prepare for war.