This paper investigates galloping-based piezoelectric energy harvesting (EH) in a linear two-degree-of-freedom (2DOF) mechanical system coupled to an electrical circuit through a piezoelectric mechanism. The 2DOF galloping-based harvester consists of mounting a primary piezoelectric system on a secondary structure with a bluff body at the tip of each beam. A comparative study is carried out by examining two configurations. In the first classical configuration, only the primary structure (with a bluff body) is excited by an aerodynamic force. In the second configuration, it is considered that the primary and secondary structures (both with a bluff body) are both exposed to an aerodynamic force. The modified complexification-averaging (CX-A) method is applied to obtain analytical approximate solutions of the amplitude and output power for both configurations. To validate the analytical results, numerical simulations are performed. The energy harvested from the second configuration and that harvested from the first configuration are calculated and compared. It is shown that the presence of two aerodynamic forces enables the 2DOF system to harvest higher power compared to the conventional 2DOF galloping-based EH system under a single aerodynamic force. Also, it is demonstrated that in the second configuration the harvester may have a low critical wind galloping speed. This study may provide a theoretical design and optimization process that can be used to give guidelines in the design of 2DOF galloping-based piezoelectric energy harvesters under two aerodynamic forces.