FileUpload with list binding in RepeatingGroup fails to render when data model has 2+ pre-populated values

[magnusrf]

Description of the bug

When a FileUpload component inside a RepeatingGroup has 2+ attachment IDs pre-populated in the data model, that specific FileUpload node fails to render. The files don't show up and an error message is displayed in place of the component.

Exception thrown when generating node "fileAttachment-designs-0": Error: Trying to redefine non-empty obj['attachmentId']

Steps To Reproduce

1. Have an app with a RepeatingGroup containing a FileUpload with dataModelBindings.list
2. Get 2+ attachment IDs into that list field (via API prefill, XML upload, or backend logic)
3. Load the form — the FileUpload component shows an error instead of the uploaded files

we're having issues for this form https://altinn.studio/repos/pat/design

Additional Information

No response

[HauklandJ]

Tagger taskforce next fordi de sitter på kompetansen for å løse denne