Getting duplicates when I don't even have all the items

I have about 50 to 60 items for each hero in the game, that’s about halfway of each hero and in every lootbox i get at least 1 duplicate. You’d think that duplicates would start appearing after you have 80 items or more on each hero.

You’re probably missing mostly epic and legendary items then. Since you get 3 grey items in a lootbox most of the time it’s normal to get duplicates for them earlier than more rare items.

Here’s my guess: you own every single rare (blue) item in the game. Therefore, any rare you receive has to be a duplicate.

I get duplicates too I own almost all the commons and uncommons… I’m just grinding the coins and get an occasional legendary. My tip keep grinding those coins for events and buy like cheap 1k legendaries with the coins you hoarded

Hard to say what to reward you with when you play 100x more than a causal player or even more. This getting stars and different frames was a good idea from Blizz because empty frames without stras look ugly so getting them back is something to grind for. As of items, money in this game means nothing. By the time you hit silver frame you will already be getting mostly dupes and have 20-30k gold in your stash.
What they could do with all this useless thingies is for example to create a speed queue where you can queue up with your extra gold.