Just discovered a second variation of the 6th issue Star Club card from the North Star Mohican Casino in Bowler, WI. The originally listed card is dark green and the new variation is light green. But the main difference is in the position of the text on the back. The text is identical as to font and spacing but on the originally listed dark green card the text is approx. 7mm below the mag stripe. On the new found light green card the reverse text is approx. 5mm below the mag stripe. Seems they moved the text up slightly on the new found card.
Here's scans of the original card and the new found card for comparison.