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We recently imported a pst for a calendar file from a users account at their old company, into their current exchange account.

Around a week after the importing, the calendar has gone completely crazy. Some items, for example birthdays that reoccur have created, in one case, 3200 copies of itself on the same day, same year etc...

It looks like there are a few tools for removing duplicates, and I have thought that perhaps we could use one of those but it seems like spraying a water bottle on a burning home.

I attempted to go into list view, order everything by subject and remove all but one. This didn't help.

I attempted the same thing, this time planning to remove all the entries and recreate. Even though I removed all entries in the list view, they are still visible in the calendar view, which I cannot explain beyond it being VERY strange.

We are running Exchange 2007, Outlook 2010 32-bit on Windows 7 pro 64-bit.

Any ideas?? The calendar is getting to almost 300MB itself!

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I had to go in and remove a whole bunch of duplicates manually to get it to a manageable size, then I was able to run ODIR and it seemed to do a good job of detecting duplicates. I haven't imported the pst back into outlook, but if there are problems I will post a follow up. I am mostly just posting this to provide info for anyone who would happen to stumble upon this on google.

The root cause, I think, was that the exportation went wrong. The .pst file we received was around 280MB, which is three times bigger than it needs to be.

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It didn't work. The duplicates are still being created, but at a slower rate. It seems the rate of duplicate creation is correlated to the number of machines that are currently syncing to that inbox, several of which were (and need to be in the future) macs running Outlook 2011. I have for now removed all except one mac from the account and, again, this seems to be helping, but a few duplicates are still popping up every once in a while. I will update again if and when I find a good solution. – Stew Nov 10 '11 at 9:38

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