Product import does not replace attributes

Hi, I need to change product categories for a great many products, so the only feasible way is to do this with the export/import functions and make my changes to the product categories in Excel.

However, when I import the products back into the Store Manager, I find that the new categories are just being appended to the old categories. In other words, if a product originally belonged to Category A and I want to remap it to Category B, after import it now belongs to Category A -and- Category B.

My import file has two fields - ID (as the unique key field), and Categories (which is the pipe-delimited list of product category paths).

About the import properties:

* Since I don't want to create new products or overwrite any of the other attributes of these products BESIDES the Category paths, I'm using "Modify" not "New".

* However, since Modify will by default append the data to the existing data, I open Advanced options and for "What do we do with existing attributes?" I specify "Delete existing, add new from file" rather than the default of "Keep and update existing, add new from file".


In the end, it doesn't work as expected.

How else can this be done?