The aim of the paper is to investigate how the dual brand of firm decides its optimal allocation of advertising and fundamental strategy of marketing under taking account of markets with multi-consumption externalities. We assume that the market is multi-consumption externalities, and advertising may function as a device to coordinate consumer expectations of the purchasing decisions of other consumers, which is different from the past assumption that consumer type is single and role of advertising in market. Therefore, we reexamine the firm with optimal allocation of advertising. Finally, we show that the firm will adapt different pricing, allocation of advertising and strategy of marketing when facing the different consumer type of combination proportion. If market is dissimilar consumption externalities, above statement will be more significant; On the contrary, if firm facing similar consumption externalities, the optimal is single strategy. In other words, it is independent to consumer's type of combination proportion.