1. A multiple heat exchanger comprising: a first heat exchanger having a heat exchange core including a plurality of tubes through which a fluid flows and fins provided on outer surfaces of the tubes, and reinforcement plates for reinforcing the heat exchange core; a second heat exchanger arranged in parallel to the first heat exchanger in an air flow direction, having a heat exchange core including a plurality of tubes through which a fluid flows and fins provided on the outer surfaces of the tubes, and reinforcement plates for reinforcing the heat exchange core; and fastening means for mechanically coupling the respective reinforcement plates of the first heat exchanger and the reinforcement plates of the second heat exchanger in a state in which the reinforcement plates are to next to, and overlap, each other in series in the air flow direction.