Symptoms
It is possible for a taxpayer to cancel a NFC-e that was issued in duplicity, if another NFC-e was issued for the same transaction in contingency mode.
Resolution
The hotfix releases a new event called "Cancellation by Substitution", that was introduced in the NT 2018.004 technical notes, and is applicable for NFC-e (model 65) only.
Enable the "Cancel by substitution" parameter on the "Manage electronic fiscal documents with unknown status" form to apply this type of cancellation for original documents, that have a duplicated document registered in the contingency mode.