Some time ago I hired a web designer to create HTML template. Today I have found the same design used by many other websites. So most probably he just downloaded a free template and sold it to me. So I would like to know if there is a tool which can I use to check out the designs, something like copyscape for articles. Do you have any idea?
Not that I know of. Design, in and of itself, is not copyrightable. Unless the same images are being used, there is nothing illegal going on. Many sites have the same design because it is what works in a particular niche.