If you receive a duplicate piece of armor (or have any "extra" legendary armor/guns) save it until your group forgets that you picked it up. Then, at a place of your choosing, break away from the group without telling them. The farther and more out of the way you are, the better. then, dismantle away. It gives everyone near you a "bla bla has received 3 ascendant shards" identification. Then just say something like "oh sweet, i never get shards from this chest." Then grab a snack and enjoy :]