I've been sorting through all my Harrah's cards to find all the different cards and player number prefixes combinations I have if anyone is looking for these. They're on a separate page on my slot card trading website where I've been listing all my current doubles and other casino items for trade. There are almost 70 different Harrah's card/prefix combinations currently shown and I have LOTS of doubles for many of these.

For anyone who's interested, my Harrah's doubles can be found at
http://www.slotcardtrader.com/harrahs.htm