[DNSB]

To be a bit repetitive, run the Find Duplicates plugin in library mode from your main library pointing the library to check for duplicates to your magazine library and delete the files indicated as duplicates before you do the transfer.

See the attached images for the dropdown menu and the cross library search options. In my case, I am searching my main library for duplicates of books in my intake library before cleaning them up.

For your use case, use the file browser beside the library name box to select your Magazine library, set the title/author bits as you want and click on okay.

Pretty easy-peasy.