Underground Comix are known for using different prices, covers (art or color variations) and/or interior content to distinguish between printings.
1st print July 1970 has 0.50 USD cover price. Chair on cover has yellow corner.
2nd print has 0.50 USD cover price. Chair on cover now all red.
3rd print has 0.50 USD cover price. Advertisement on inside back cover now has 9 covers shown.
Sequence on back cover of issue.