I recently bought a blueberry plant and have it in a whiskey barrel filled with sphagnum moss. The plant has two apparently new growth shoots about 3 feet tall. These shoots have branching at the top with buds on the branch tips. On other plants I would call these "suckers" and would prune them off. As I have limited knowledge about blueberry plants I am unsure whether to leave them or cut them off.
I would cut these new shoots off about halfway to encourage branching. So cut the one with the two main branches right about the first branch and other one cut off at about the same height. This will encourage the plant to branch as well as send up new shoots from the base of the plant. You are right in that you usually remove the suckers, but in this case you want to leave them. These new suckers will be the fruiting shoots of the future. As the shoots which are on the plant now age, they need to be sequentially removed over time. So in a couple of years you will cut the shoots that you have right now totally to the ground to make room for the new shoots. Larry Stein, Extension Fruit & Nut Specialist.