Just unearthed a slightly different variation of the 5th issue card from the Mirage Casino in Las Vegas, NV. This is The Ultimate Dollar Slot Club card with the PPC manufacturer mark that has no comma. What I noticed is there is a slight difference in the font used for the patent number printed in the bottom right corner on the back. On one card that text is about 14.5mm wide and on the new found card it's 16mm wide.

Here's a scan of the front then scans of the original card with the 14.5mm patent# and then finally the 16mm patent#. The difference is pretty noticeable once you know it's there.