A guess here --
The older $1 CC chips have all had a base color of white or cream. A number of them over the years, as seen on Chip Guide.

The latest $1 issue has a blue base color. See pic, from Chip Guide --

Perhaps they have fully changed over to these blue $1's, throughout the property, and now an cream or white is considered obsolete. I haven't been there recently, so that's just a guess. Maybe that's what accounts for the activity you're seeing on the white ones?

BTW, the ones in your picture were all rack chips, as far as I know.