Duplicate folder exists for two different item types and cannot be mapped.
This error indicates that MigrationWiz detected two or more folders of different item types, such as Contact and Mail.
We recommend the following:
Have the user log in to their Source environment and rename one of the offending folders.
Resubmit the migration.
Note: Most systems do not allow the creation of two folders with the same name at the same hierarchy level. For example, with Microsoft Exchange Server, you cannot create an email folder called "My Contacts" if there is another contact folder with the same name "My Contacts". For this reason, MigrationWiz alerts you of the name conflict by reporting an error.