"I suspect it arises when an 'unknowing' cage person cashes them in by error..."

I would suspect that one of the first things a cage person is told ... is NOT to accept silver strikes from other properties ... or else they won't remain as a cage person for very long.

I would also suspect that a "unknowing" cage person would ask a supervisor when in doubt. It has been my experience that some casino employees can't even blow their nose without asking permission from their boss first.

Uh, oh, I also suspect that I'm in trouble now ... but before the flame throwers are ignited, remember ... I said "SOME"!