@jea48 , then is the way OP did it
The OP has a 3 wire multiwire branch circuit. He’s stuck with what he has. He has two separate circuits that must be fed from both legs that share a common neutral conductor.
preferable to running two circuits of 10-2 with two separate neutrals?
And on edit: what would be the reason/advantage for using two runs of 10-3 vs two runs of 10-2?