We address a supply chain wherein a manufacturer supplies two newsvendor-type items to a retailer who sells the two items with two distinct retail prices in a stochastic demand market, allowing demand leakage from the higher-priced item to the lower-priced one. The objective of this study is to determine the two items' order quantities, retail prices, wholesale prices and buyback prices to coordinate the chain and create a win-win situation, from which we learn that the buyback commitment is Pareto-efficient and can enhance the chain's profit proficiency when facing high demand uncertain markets. Many significant managerial insights regarding demand leakage and demand uncertainty are observed hereafter.