We are seeing an odd issue where duplicate exchange accounts are created in a user's Outlook profile when their Office version gets upgraded from 2010 to 2013.  We discovered this when users' mailboxes started getting migrated to Exchange 2013, they would be able to receive mail fine, but when sending the messages would sit in the outbox of the second account.

We're currently trying to discover the full scope of users impacted by this, I'm attempting to write a script to check in their user reg hive for the duplicate accounts but I need some guidance as the reg keys in outlook profiles are not very easy to read or intuitive, some keys seem to be consistent between different users on different machines, but I need to figure out a definitive way of determining when a user has duplicate accounts configured in their profile.

Found this thread:

http://blogs.technet.com/b/odsupport/archive/2010/08/06/multiple-exchange-accounts-created-in-outlook-2010-with-existing-outlook-profiles-after-upgrading-from-an-earlier-office-version-using-a-custom-msp.aspx

which is basically the same problem but it only tells you how to prevent it from happening, I need to figure out how to fix our users' profiles now that they've been upgraded.