If a donor collection is renamed during a tenant migration, the recipient aborts the migration. Possible mechanism:

1. Recipient opens cursor on donor collection by UUID.
2. Recipient clones some documents.
3. Renaming the collection on the donor kills the cursor.
4. The recipient considers the error retryable, and opens a new cursor on the renamed collection (by the same UUID).
5. Using the new cursor, the recipient begins cloning from the beginning.
6. The recipient tries to insert the same first document, generating a DuplicateKeyError.

I'm not sure this is the correct diagnosis. And, once the DuplicateKeyError is fixed, make sure the recipient ends up with a collection that is properly named, and does not have a collection with the old name.