LSB Extra Shards

Hey just wondering before I buy any of these new LSBs, does anyone know if you get extra shards for the shard store if you already have one of the characters in the pack at 7 stars? Or if the relic levels are additive at all? For example I'm thinking of getting the Finalizer and Raddus packs, and they both include Bossk and Hound's Tooth. Does Bossk get boosted even higher in this case, with extra shards to spend, or is it just a wasted overlap?