Generating a usable category catalog from photos tagged in the Windows Photo Gallery

[HaiStein]

I would like to create a photo database for our office, in which I can tag photos with keywords or outline terms with which my colleagues can filter them out again. For this I need a through all usable category catalog.

I already have a lot of photos provided with hierarchical keywords in Windows Photo Gallery. When I import them into XnView MP and write a catalog from them, the categories are always duplicated.
Once Categories and Subcategories:
-Structural Details
-Borde
-Angular shelves
and once as a slashword keyword chains:
Structural details / Borde / Schrägborde.

If I delete the duplicates from the category catalog I have the same problem again, when I import new photo.
What am I doing wrong? Is there a way to suppress the keyword strings during import?

[xnview]

could you send me a sample file?