Hey Gene, there are (MOD) modified listings to these chips, as the stickers were indeed, modified. They are also listed as (MUL) for Multiple Notes, as on P. 387 stating the following:
N9970 Horseshoe Club-- Red & Silver 1994 sticker added to 1991 chips. Yes, they are fakes. The red or silver stickers were pasted over the actual yellow inlay.