Override auotmatic Category Slug creation

Hi,
Why does WordPress (2.6.1) automatically add the parent category name to a sub category slug? Unless I’m missing something, and I looked everywhere, it does this automatically upon creating new sub categories. Editing them won’t help either, I’m not able to change them either – it doesn’t give me an error but just closes the edit page quitely, and it always adds the parent to whatever I write again.

Example:
Parent Category “Shoes“
|
Child Category “Running Shoes“
|
Child Category “Sandals“

Permalink for Running Shoes is
mysite.com/shoes/running-shoes-shoes/postname

Permalink for Sandals is
mysite.com/shoes/sandals-shoes/postname

This is a bit annoying, and I’d appreciate any help on this one ??