When the conventional current comes back from the negative(ground) wires, shouldn't the voltage be the same? 12V(red) in and 12V(black) out. It is like there is a river(AC) and I split it into two smaller streams(two PSUs) and within the two smaller streams there are even more tiny streams(branching negative wires). Why would it potentially become a flood?
Is there a name for this behaviour/phenomenon that I can search for?