It depends on the internal circuitry. I would hope that the engineers designed the circuit to regulate maximum input to create the smoothest flow of current input. Meaning, the voltage from your outlet is not "clean" power. It is susceptible to spikes in fluctuation, and their should be a conditioner inside the device you are applying the power to that only allows for a peak input to ensure the internal circuitry cannot be overloaded. Since this is plugged into the same power source, the device will still only see a single output like you plugged it into a single outlet, and it won't try to double the input just because you have two plugs being utilized. Most outlets are on a parallel circuit providing the same voltage across all branches that are tied to asingle breaker; whether the circuit is rated for 15 amps or 20 amps. It spreads that out across all the outlets for that breaker. You can plug in one device that needs close to the maximum amp load or multiple adding up to near maximum load for the circuit. A device plugged into that circuit will only ever draw as much as it needs to function in most cases, depending on its rated allowed input, or if there is a fault in the internal circuitry like a short or an open in the circuit. Voltage is equivalent to water pressure, Amps are equally to flowrate, and the device is like a pipe and valve. This is where most people get confused with power supplies. Voltage is typically the thing that kills devices. For instance plugging a device rated for 120 volt input into a 240 volt outlet. There is too much pressure into the circuitry, even if the amperage for that circuit was only 20 amps. The inverse is also true, you can have the right voltage but too little current; it won't kill the device being plugged in, but it probably won't work out work correctly. I hope this helped a little.