duplicate titles on many urls

Hi

I am getting duplicate titles on these urls and i want to therefore change them.
I am not clear where wordpress is taking the title for each url.

domain.com/costume/category/70s-dress/
domain.com/costume/category/70s-dress/page/3/
domain.com/costume/category/70s-dress/page/4/

Each of these urls is a page with 3 posts in it
And these 3 posts are different in each url
So where does wordpress get the title for above urls and how do i get in to edit them to be different ?

thanks
John B