ValidationError: Duplicate values violate save constraint and we are unable to fix it

[sentry-io]

While debugging #4824, I found this validation error in Sentry that's preventing the main document from saving. This error is also blocking the creation of the corresponding document for associated attachments.

Sentry Issue: COURTLISTENER-840

RECAPDocument.DoesNotExist: RECAPDocument matching query does not exist.
  File "cl/recap/mergers.py", line 1670, in merge_attachment_page_data
    main_rd = await RECAPDocument.objects.select_related(

ValidationError: Duplicate values violate save constraint and we are unable to fix it because the items have different pacer_doc_id values. The rds are None and 376976961 
(12 additional frame(s) were not displayed)
...
  File "cl/recap/tasks.py", line 115, in process_recap_upload
    await process_recap_attachment(pq_pk)
  File "cl/recap/tasks.py", line 760, in process_recap_attachment
    rds_affected, de = await merge_attachment_page_data(
  File "cl/recap/mergers.py", line 1766, in merge_attachment_page_data
    await rd.asave()
  File "cl/search/models.py", line 1533, in asave
    return await sync_to_async(self.save)(
  File "cl/search/models.py", line 1504, in save
    raise ValidationError(

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Filed by @ERosendo

[mlissner]

Do you see a path to a fix?