I am trying to update my stocktake and I get a warning telling me I have duplicate product codes but when I view the list there is nothing on it.
This is because you have a blank product code sitting in your Product table. Please call either your Partner or the Support team to have this removed.
Once the blank code has been removed the update can be re-done. If any genuine duplicate appear they will be listed on the report and can be deleted as deleted as necessary.
Partners or Support see here