What on earth have I done?

For example: http:www.mysite.com/contact_us/

now reads: http://www.mysite.com/contact_us/contact_us/

I'm not sure if I should have posted this in the webdesign section or here as this occured only after I uploaded WP using Dreamweaver. (yes, I had intended to use WP on my host's server. I am freaking out as I can't see how to rectify this as the actual website's files appear normal, in both local and remote view. *cry* Also, when I navigate through the site, the links still work, but they read as I have shown above. Oddly enough, the index page doesn't have this double up, but just the other pages. HELP!