Outlook Calendar Issues

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Outlook version
Outlook 2011 for Mac
Email Account
Exchange Server
Hi All,

Hoping for some assistance. My company recently moved to a new Exchange Server 2010 SP3 from Exchange Server 2010 SP2. Our environment is Outlook for Mac.

We had to do a cut-over of our mail so an export/import into the new Exchange server.

We've run into several issues with the process.

1. Duplicates - Calendars are seeing lots of duplicates of appts. From dozens to hundreds of duplicates for some items.

2. Times off - Some appt times are off by an hour

3. Outlook for Mac and OWA not in sync - Even after removing the duplicates using an Outlook 2010 plugin. OWA reflects correctly but Outlook for Mac doesn't (Even after emptying cache and creating a new identity it's seeing a duplicate for some calendar items.).

There's a couple of things about our environment that I believe contributed to the issue.

1. Multiple delegates - Apparently a lot of the users who have the numbers duplicates also had numerous delegates on the calendar with publishing editor rights (Sometimes upwards of 15 people).

2. Outlook for Mac when setup with a new identity apparently defaults new appts. to Indian Eastern Time (This I just discovered)

We've opened a ticket with Microsoft but still haven't gotten a cause. I've been able to reproduce the duplicates. Apparently when editing a calendar item it creates a duplicate but the duplicate created isn't always modified by the person who made the change, sometimes it's by one of the other editors. So Outlook is creating duplicates that are modified by another editor (Keep in mind I tested this in webmail and it happened).

It seems like there's some type of corruption that possibly happened.

Has anyone seen anything like this? It's only been the calendar that's affected. Everything else is working ok. Microsoft initially tried to fault Activesync but we've always been using Activesync. The duplicates weren't an issue until the cut-over.

I believe I was able to fix one user by removing all delegates, running the duplicate removal tool, then re-adding delegates. After that no more duplicates seem to be replicating even when modifying items. But I'm still seeing inconsistencies between Outlook for Mac and OWA.
I have not seen that behavior but I'm thinking a couple of things probably contribute to it.

1) Import/Export creates new items, with new EntryIDs. (Move would not, but it's more labor intensive, much more.)

2) Syncing with a smartphone that wasn't cleared. The device picks up the new EntryID and see it as a new item.
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