Adding Parallel Diodes to a load
The diodes drop less voltage when the current through them is less. If you  parallel three perfectly matched diodes and maintain them at exactly the same junction temperature, the current will split evenly between them so it will be 1/3 through each and the voltage drop will be a bit less. 

For example, compare the 1N400x diodes: 



If you reduce the current from 300mA to 100mA each, the voltage drop will decrease from about 860mV to 790mV at Tj = 25°C. 

Of course, in reality the diodes are not going to be perfectly matched and the junctions will not be at the same temperature (especially if one of them starts hogging more current it will get hotter than the others).