Last year, I ordered a bareroot sugar maple sapling online from a nursery. It arrived with the proper packaging (roots wrapped in damp paper) and I planted it in the ground while it was dormant. But when it broke dormancy, the buds never leafed out and instead a second side shoot sprouted leaves (pictured above this past November), growing almost as tall as the main (dead) trunk. Will it be able to survive in the future? And if so how can i train it to have just one main leader?
You can use the dead stem as a stake to keep the new live stem growing straight for this upcoming season.
I would prune that dead stem off in the fall, after leaf drop. The live stem will assume "leadership" responsibilities.
Yes by all means try to keep the new piece growing straight. In my experience maple trees can be hard to get them to go vertical if they suffer deer nibble or die back such as your tree. Your tree should survive just fine. I would remove the dead piece after the living portion has leafed out this spring/early summer.
