When using Resume Extractor, it will detect if a record already exists and ask if you want to overwrite. If you choose yes, it overwrites the resume attachment  or any attachment) that may already exist in the candidate record.    It would make more sense to preserve the previous attachment.   I've tried playing with the attachment category and that doesn't help.   If you use Resume Extractor for a Linkedin profile refresh and the attachments already in the record are gone.

Updating candidate resumes using the extractor should be easy without losing prior attachments.