Yes, I'm pretty sure those chips with pinback inlays (proto-crest & seal chips) are slightly pre-1900. Richard did a great job of figuring out the Whitehead and Hoag connection, which he describes on his website.

I haven't found them listed in a pre-1900 catalog yet, but I came across an 1899 article that convincingly describes them.

Below is an excerpt from an article published on 11/26/1899, New York Evening Sun, about how poker chips had recently become so attractive that more women had started buying them. "A sort of patriotic poker chip has recently come to light. It speaks of the Anglo-American Union by showing the national flag on one side, while it displays the English flag on the reverse."

The chip being described is this Whitehead & Hoag inlay chip, that you uploaded to the ChipGuide a while back.

There were actually a couple of chip manufacturers trying to figure out how to make Crest and Seal type chips pre-1900. I’m slowly working on an article about the early history of poker chip development and manufacturing, before the USPC Co. got into the business.