As (configuration required: duplicat= false and archive activatedAs mentioned before, the Kepler - Attachment fields | simple & multiple custom field can be configured to store multiple files.
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3. Add a new version (modified) of an uploaded file, the new version will be attached and the old one will be added to the archive (configuration required: duplicatAllow Duplication = false and archive is activated)
PS: When users attempt to attach empty files to an issue an "Empty File Warning" appears, the attachment process is not blocked so users can proceed as needed.
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