If a user creates a calendar event and invites another person within the company (within Zimbra), the message goes out via e-mail inviting him/her. Even if iCal is not set to automatically accept invitations, the event appears in his/her calendar automatically (probably through the iSync services)...but there is no ability to accept/decline.

If he/she double-clicks the .ics attachment from the message, a notification shows up in iCal (with option to accept/decline), but then iSync services (or whatever) has already populated the calendar with that entry (ARGH!). So, if the user accepts or declines that notification, he/she now has two duplicate calendar entries.

If he/she then attempts to resolve the duplicates and nukes the .ics generated entry, the user then has no ability to delete and not notify the meeting originator, which then confuses that user as to whether the recipient actually declined or accepted the meeting.

Is there a way to use the iSync services AND get the ability to accept/decline meetings AND not generate these duplications? I think we're having a logic puzzle here and we're losing.