How does electrical signature devices work when there is more than one load connected?
It looks like they have 3 ADC's so they are doing more than current monitoring, and a CPLD, which probably means they have real-time constraints and need even sampling. 

 
Source: http://whatnicklife.blogspot.com/2017/12/sense-energy-monitor-teardown-sampling.html

Could there be a difference in this circuit? Souldn't be do hard from only looking at the graph of the voltage and the current. 







simulate this circuit &ndash; Schematic created using CircuitLab

Even refrigerator doors can be detected opening:

Source: The Determination of Load Profiles and POwer Consumptions of Home Appliances

On top of that each SMPS has a frequency signature from noise and harmonics. 

How they are actually formulating the AI and neural network? Ask them.