Diaphragm pump features upper/lower diaphragm pumping assemblies (U/LDPAs) for pumping fluid and a manifold assembly arranged therebetween. The manifold assembly include a manifold body having an inlet with dual inlet ports and an inlet chamber to receive the fluid from a source; an inlet check valve assembly channel having an inlet duckbill check valve assembly (DCVA) arranged therein to receive the fluid from the dual inlet ports; U/LDPAs orifices having the U/LDPA arranged therein to receive the fluid from the inlet DCVA via first upper/lower manifold conduits and provide the fluid from the U/LDPAs via second upper/lower manifold conduits; an outlet check valve assembly channel having an outlet DCVA arranged therein to receive the fluid from the U/LDPAs; and an outlet having dual outlet ports and an outlet chamber to receive the fluid from the U/LDPAs and provide the fluid from the pump to a outlet source.