Some people "verify" based on the first positive Google hit. Take the chips used at AMVETS posts, for example. If we find AMVETS Post #1, it could come from any of 50 states since each state numbers its posts starting at number 1. If you ask for its identity on The Chip Board, you will get numerous responses, each insisting their state is correct - and they will even add the detail of a specific address or the post's website. But unless the chip says "Dallas" or "Los Angeles" or "Detroit," we really don't know for sure. If they all start showing up in Denver, we have a good guess - but only an educated guess that comes from putting our heads together.
With very old chips, it is less likely that someone can say "I used to gamble there, and I have a stack of those in my dresser." We have to rely on manufacturer records quite often - and I'm glad so many contributors to the Chip Board maintain those records so we can all learn.