Hi, I started mango from seed and now it stared to grow it's next set of leaves, or I thought it was. Just looked at it last night and it looks like it is growing 3 branches. From what I have seen of mango's they grow up without branching for a while. But for a mango start branching on the second set of leaves, Is that strange? won't that make the tree very short? And no the seedling was not topped, cut or touched in anyway.
I don't know how normal it is to grow such low branches, but you can prune off any branches that you don't want.
There a chance not all the side shoots will survive since the weaker ones are shed naturally. I think it would be nice to end up with a lower branching tree since that will result in one with denser foliage. This is a tall tree tree that is being grown indoors so the sooner it branches the better otherwise the leaves will be too close to the ceiling.
I would let it grow naturally for now and see what happens. It looks like the leftmost shoot may be shed but I would probably remove it anyway even if it weren't. I think the tree would look best and be stronger with one leader and a side branch.