Article count incorrect

Hi,

While trying to export my products for a price update, I stumbled upon something that caught my eye.

When I set the products/variants filter in the product list to 'Products', I get 302 results
When I set the products/variants filter in the product list to 'Variants', I get 638 results
When I set the prodcuts/variants filter in the product list to 'All', I get 1117 results

I checked with my calculator, which claims 302 = 638 = 940. So with the 'All' setting I end up with 177 'ghost' products...

When I export all product and variants, I get 940 products (after stripping out the categories, which by the way, do not seem to be related to the difference found).

Is it possible that my database is cluttered with non-used variants and should I worry about that? Or is this really a bug?

Thanks,
MF