When I asked the $50 D7 template purveyor, why some of their source files were virtually identical to a template provided free, they asked, "Is it the same template? If it is, I will remove.... bla bla bla" Not the response you would expect if the person were sellling their own work.

What are the odds that custom images would have the exact same name? .... especially when the name is name is 16 characters long. Pretty slim, in my opinion.