When a stub object responds to a meeting request that user or contact is added as a duplicate optional attendee that has accepted the meeting request.
To resolve this issue and not have the attendees duplicated you will need to remove the display name mapper.
Modifying the display name for both users and contacts will cause Outlook to duplicate and add that user or contact as an optional attendee that has accepted the meeting request.
If the display name is not modified for both users and contacts Outlook 2010 will not duplicate the name.
This behaviour differs slightly if outlook is not used. If you are only using OWA on the User or Contact with a modified display name will be listed as not responded to the request under meeting tracking. As soon as you open up Outlook that user will be added (duplicated) as an optional attendee that has accepted.
This is a function of Outlook and how it handles meeting responses and not an issue with QCS.
