As a young plant I wouldn't be too concerned about the number of branches. I have been known to cut back some of the branches that will serve no useful purpose as an adult plant which will give more energy to the remaining ones, and shape the tree. As for planting another right next to it, I wouldn't. 5 years from now when you have two twenty foot trees growing into each other, it will be a mess. We have nasturtiums and herbs underneath and a gloriosa lily growing up the trunk of our Kadota, and everybody is happy.

Good luck

Terry