Reading the reviews here and elsewhere, port 1 is designed so that, if your device can negotiate with the power supply, it can provide more voltage, (provided the power supply can output more power. Don’t know what would happen if you plugged another device into 2 at the same time, if that voltage would be 5 or 10?? I don’t have one yet, and I am guessing about this. So, please confirm elsewhere. But, this should give you a clue.