Ignored and Duplicating Activities
All activity commands ignore any:
pre-work
activities with status set to 'cancelled' via the Inbound API
activities with status set to 'deleted' or 'suspended' (regardless of how the status was set)
activities scheduled for the past date
Thus even if any of the above-mentioned activities have the key fields, they are not considered among the existing activities and treated by the Inbound Interface as if they do not exist (e.g. if a command is set, and the key fields are present only in the activity canceled via the Inbound Interface and/or in a deleted activity, they will not be considered and a new activity will be inserted).
If there is more than one activity with the same key fields, the activity with the maximum ID is processed and the rest are treated as 'duplicating' (and canceled/deleted in the end of the transaction).