When Jarrison Time is connecting to an access control database as an import location, it may be best to Initialize the access control database for the first import.

Initializing the database will mark all clockings as imported. Thus when the first import is run, manually or via Device Engine, no clockings will import. You will need to do a re-import for a date range, if older clockings are required.
If the external database is not initialized, Jarrison Time will import all historical clockings.