Since it's not possessive...how about the purpose of indicating plural of...? As in quantity of casinos operated by... OR, maybe it's an error. <g>

Though there are (was) more than one manufacturer making full graphic ceramic chips....I think the examples you show are Chipco Int'l. Casino Bled and some of the older houses in Prague used the other (?) manufacturer's chips, as did some small casinos in Bulgaria and Turkey. I know B&G was their distributor at one time. I once showed the chips to John K at a trade show.

JB