The objective of this study is to explore the gambling participations and game purchase duplication of light regular, heavy regular and pathological gamblers by applying the Duplication of Purchase Law. Current study uses data collected by the Australian Productivity Commission for eight different types of games. Key behavioral statistics on light regular, heavy regular, and pathological gamblers were computed and compared. The key finding is that pathological gambling, just like regular gambling, follows the Duplication of Purchase Law, which states that the dominant factor of purchase duplication between two brands is their market shares. This means that gambling between any two games at pathological level, like any regular consumer purchases, exhibits "law-like" regularity based on the pathological gamblers' participation rate of each game. Additionally, pathological gamblers tend to gamble more frequently across all games except lotteries and instant as well as make greater cross-purchases compared to heavy regular gamblers. A better understanding of the behavioral traits between regular (particularly heavy regular) and pathological gamblers can be useful to public policy makers and social marketers in order to more accurately identify such gamblers and better manage the negative impacts of gambling.