What is the difference between the two, Why is the game treating them as different items ?

So I used a shop mod, and the item that its set it to is the one in the image. 
My give command is give SomeVagueRanks feather[custom_name='["",{"text":"Dynmax Powder","italic":false,"color":"dark_red"}]',lore=['["",{"text":"Born to distort Space and Time","italic":false}]','["",{"text":"Forced to be traded around for cash","italic":false}]','["",{"text":"This powder can be sold to the Dynmax Researcher for 50$","italic":false}]'],custom_model_data=1]
Why are they as non-stackable different items ?
Yes they need to be the same as I need a command that will happen when you defeat a boss.