I suspect it arises when an 'unknowing' cage person cashes them in by error - as of course has been known with obsolete chips

A couple of casinos save me all their foreign strikes - Last time I got some from Mississippi and Colorado.

I guess they all make their own rules - just like the procedure for new releases. (Lets not start that one again!)

I dont ask why - I just buy them - as I am sure you would!