Customer:Job: XYZ is duplicated in the QuickBooks file
Where "XYZ" indicates the customer name that is causing the error.
Cause: A customer either exists under the same name as a customer, vendor, other name or employee. This happens when using IIF tools that bypass the data validation in QuickBooks or as the result of index corruption.
Step 1. Check the customer other QuickBooks lists (vendor, other name, employee, item) for the same name. QuickBooks should not allow the same name to exist across multiple lists. Be sure to include inactive names (using the filter dropdown View All or checkbox Include Inactive) when doing your search.
Step 2. Try renaming the customer in QuickBooks that it is failing on and then rename it back to the correct name.
Step 3. Do a rebuild of your QB file (File/Utilities/Rebuild Data)