Pages/Posts URL conflict

I have a page example.com/X
I was writing a blog, I named it "X" so the url would be example.com/X, but normally wordpress will rename the blog to example.com/x-2. You can't have two pages with one url...

All of the sudden my WP isn't stopping me from making duplicate url's. It's even showing both the page/post differently in different areas.

Wha?!