.ics import creates duplicate event in Outlook

Question

These three threads cover my issue, however none of the solutions worked for me.

• Help updating an event in Outlook 2007 with an iCalendar file (2)
• Delete calendar event using iCalendar file import (Outlook 2003 problem) ? (3)
• ICalendar and event updates not working in Outlook (7)

Each time I import an .ics with a modification or a cancellation, Outlook creates another even versus, updating an event or cancelling an event.

Does anyone have any other solutions to offer?

Thanks!