This is a usability issue rather than a specific "bug". It was discovered in the testing of https://github.com/DSpace/dspace-angular/pull/279
When automatic metadata extraction is enabled for DOIs (or similar identifier fields), extracted metadata may sometimes get duplicated in the workspace item without notifying the user. This only occurs in the new DSpace 7 REST API (as it's a new feature there).
For example, if you update a PDF into DSpace 7 Angular UI, that PDF's metadata will be extracted to start a new workspace item. If the user then adds a DOI (and the DOI metadata lookup is enabled), then additional metadata may be added to the workspace item from the DOI.
While in some scenarios, this is a great feature, it can result in duplicate titles/abstracts/etc if the DOI metadata differs from the PDF metadata by just a single character (e.g. a period or comma).
Ideally, the REST API should notify the Angular UI when a metadata update is about to occur. We may even want to prompt the user to "approve" or "reject" an automated metadata update. Currently, this update is entirely on the server-side, and new metadata suddenly appears in the submission UI (without any notification or approval).