Zotero hidden preferences https://www.zotero.org/support/preferences/hidden_preferences#general_preferences

Important: attachmentRenameFormatString → {%c - }{%y - }{%t{160}}

Files can be added to your Zotero library as either copies or links. With copies, a copy of the original file is stored in the Zotero data directory. File copies are synced if file syncing has been set up. In contrast, when a file is linked, Zotero only stores a link to the location of the original file. Linked files are not synced.

https://forums.zotero.org/discussion/34463/convert-linked-file-attachments-to-stored-attachments/

https://forums.zotero.org/discussion/63790/duplicate-citations-in-word-how-to-remove