This is for the sake of the library, the squishy shelf & the clothing rack. 

I've noticed that items will be highlighted green in the NPC shops when present in your inventory/user shop inventory, but not when present in your collections. I often end up buying doubles of items that I think I don't have, but already do. I realise I could easily check if I already have an item in my collections via the search function, but being able to see it in the NPC shops somehow would be a nice quality of life feature to have- even if it was just some italized text, (ie, COLLECTED) or a little symbol showing that I have the item in collections. This would make it differ from the inventory green highlights, and make it possible to have both. 

Apologies if this has already been suggested, please lock or delete if this is a repeat. 

Please share your input! Thank you! C: