How do I find duplicate profiles?

How can I find out if there are other profiles that may be duplicates of people in my family tree? When I first entered the new relative on my tree, several possible matches appeared in a list. I checked each of them. None were matches, so I created a new person. The other day, I swear I came upon a page listing possible duplicates for several people in my tree. I've looked all over, but cannot find this page again. Was I mistaken? Is there such ab page? If so, how do I find it?