Assuming you mean "journal article", that's some sort of misunderstanding. An item you add to multiple collections is the same item — that's how collections work — and you'd see the same data everywhere. If changes to one aren't showing up on another, it's not the same item, you'd see it listed multiple times in the library root, and you should deduplicate.

https://www.zotero.org/support/collections_and_tags#the_zotero_collections_model
https://www.zotero.org/support/duplicate_detection