Some companies, based on the beliefs of their managers, aim to obtain solely loyal customers in the hope that these customers will always buy only one brand and never cheat by buying a competitor’s brand. However, a growing body of empirical research suggests that this may be an overly positive expectation and that this marketing strategy can run counter to the nature of the consumer. To scrutinize the sole loyal buyer idea, this study empirically examines the phenomenon of duplication of purchase, which suggests that customers not only buy from repertoire but also that brands share customers in proportion to their market share. Data were drawn from two consumer packaged goods categories: beer (10 brands), soft drinks (6 brands), and eight NUTS2 regions. Using a robust sample of 3,488 customers from a consumer panel and many sets of data approach, the research replicated significant patterns of duplication of purchase in both categories studied and across all regions. The findings support the notion that while consumers are likely to repurchase a brand previously purchased, they also frequently diversify their choices between competing brands. Therefore, the study confirms the generalisability of duplication of purchase behaviour in different categories and geographies, providing critical information for marketing strategy and brand management. It is a strategy that goes against the principles of how buying behaviour works to try to persuade customers to buy from one single brand for the rest of their lives. A great deal of corporate resources will be wasted in the pursuit of sole loyalty.