Permalink Structure and Subcategories

I’m having an issue with my permalink structure and sub categories.

For example, my url/permalink strucutre with subcategory post is as follows:

mysitecom/parent-category-name/sub-category-name/my-awesome-post/

BUT ….

When I delete the parent category (url example below) from my url to make the post still shows up!

mysitecom/sub-category-name/my-awesome-post/

Shouldn’t this give me a 404 error since the “sub-category-name” isn’t a parent/base category? Why would my post show up in two different url structures?

This: mysitecom/sub-category-name/my-awesome-post/

and This: mysitecom/parent-category-name/sub-category-name/my-awesome-post/

I have my wordpress permalink structure set up as follows:
/%category%/%postname%/