In a bid to explore the use of an empirical-based model to explain regular gaming purchases, this study applies the Duplication of Purchase Law to gaming. Developed from empirical-based marketing theory and observed in many consumer brands, the Duplication of Purchase Law states that the dominant factor of purchase duplication between two brands is their market share. Using data obtained from the U.S. Gambling Impact Study, this study found that the duplication of games played was highly correlated to their penetration rates and hence, market share. In addition, the number of sole gamblers in each game was also related to its penetration rate. The results suggest the applicability of the duplication law to gaming. The implications of the findings to gaming businesses and public policy makers are discussed.