Heat sink less inverter

Is this a question?

as long as each one takes an equal share of the load. Just making them the same part does not ensure this as part to part variation can easily cause one to take 12 amps and another 4 for the same average current of 8 amps while the other 4 take 8 amps. The one wih 12 amps might fail from heat? So you must make sure each one is forced to take the same 8 amps. This equalization adds to the complexity and might reduce the efficiency to some degree.

This is cause by part to part variations of the DC resistance in the conducting position, which is also a function of temperature. Specifying the same batch number can reduce this problem, as can a part selection test jig. There is also correct design of the circuit.