That is exactly right. Glued into another chip. Someone trying to make a full chip again. Beware there are a lot of Frontier $5, $25 & $100 coin centers around. I remember seeing them years ago at swap meets, etc. in Vegas & they still pop up.
The real chip is black with 3 large white inserts. IT is in the book I wrote The Official Us Casino Chip Price Guide 2nd edition.