HP35s Serial Numbers Interesting Observation

[Xorand]

First of all, excellent reply Tugdual.

I suppose it is conceivable both units were manufactured close in time to each other. Did you buy them from the same source at (or nearly) the same time?

On a semi-related tangent, I had purchased a Master padlock for a storage unit from my local home improvement store a couple years ago. A couple weeks later, we realized we needed a second storage unit, so back to the same store to buy another padlock. It was a few weeks later when I thought I had grabbed the wrong key before I realized both locks were keyed exactly the same.