Rewards from weekly challenges, campaign missions, etc, are awarded once per character class. So having more than one character of a particular class provides absolutely no benefit, as far as extra powerful or pinnacle drops per week. The first of your Hunters to complete a task each week, will get the full reward. Subsequent completions with another Hunter, will only drop basic rewards. It was not uncommon back in the original Destiny, to see players with multiple characters of the same class, as you have done. At the launch of Destiny 2, the duplicate rewards were removed. This encourages players to try all three classes, and removes the advantage of over-farming gear for one class. If you wish to maximize your power gains, go with one character of each class, so that they each can boost the overall power of the group. There are plenty of power leveling guides online, to show you the most efficient methods.