They screwed up.

They missed a few when culling them out.

Same story as the Mirage $5 on the Harrah's house mold chip. BTW I sold that one for $1,500 a few years ago. 3 of them got delivered to the Mirage. As far as I know the other 2 are still there.

Letters go to gaming when these mistakes happen.

Now you know the "Rest Of The Story."