PixCompare is a really good tool to find duplicates and compare them both visually and using their properties, such as size, location, and dimension. The tool can compare one picture to a folder or find duplicate pairs within a folder. Even if one of the picture is slightly altered, the program will find its pair.
Since I own two computers, some same pictures are edited on different computers, but since both of them are perfect, its hard for me not to keep both. However, when I run out of space, I'd like to delete some of the old edited pictures. Up until this program it was hard for me to find duplicates. The pictures could only be found using the same name or same size etc. This program is different. It will find the duplicates using a hole array of methods. The pair will be matched even if one of the pictures were converted into greyscale or one of the copies was resized and so on. In my trials original and cropped pictures were matched, and the score was raised from 0 to 3. I am not really sure and could not find the information what it means, but I'd assume it gives you some sort of probability that it is a match.
The program's interface is very thoughtful, as you can delete either left or right side picture right from it. It also shows the paths to the left and right side and if you want to look at the both pictures closer (to visually compare them), then just click on the left and right picture to zoom in separate windows. Since I know how annoying it can be to find duplicates, I give this program 5 stars.