WordPress directory name in URL

I have a problem, where virtually anything written in one part of URL, still produces a valid result.
i.e http://www.domain.com/wordpressname/category

I have the domain, then the wordpress directory, then the category, post, etc. But I can type anything in the part where the wordpress directory is and it still shows posts of using the 3 category names.
i.e http://www.domain.com/anything/category

I have looked at everything and think it is down to the permalink setting, but I don’t see anything wrong with it.
It is set to /%category%/%year%/%monthnum%/%postname%/