Its very possible that they have multiple sets of chips, the approval list shows both about a year apart

WYNN LAS VEGAS 12/08/06 00/00/00 CHIP NCV THE WYNN CLASSIC NUMERAL 500 BLURPLE
WYNN LAS VEGAS 12/11/07 00/00/00 CHIP NCV NUMERAL 500 WYNN CLASSIC SKY BLUE/WHITE