Just won this on Ebay, but what do I have? $5 Nashville Nevada, diamond mold not listed in TCR and $.25 on reverse side. Floor sweep, error, Any ideas?

http://www.ebay.com/itm/Nashville-Nevada-Club-Poker-Chip-5-00-Reverse-25-Cents-/131128996753?_trksid=p2047675.l2557&ssPageName=STRK%3AMEWNX%3AIT&nma=true&si=b4tbMIMrFrLNRM%252F%252Fvwz1mEIDxq4%253D&orig_cvip=true&rt=nc