There are a number of advanced options available through ADD’s preferences which you might want to consider using.
Tag Unique Items. Any item that is not a potential duplicate of any sort will receive a “ADD Unique” tag.
Propagate Comments to Hash Dupes. With this option, sets of duplicates will have their comments copied to each other. You can select to choose the comment from the highest rated photo, lowest rated photo, or combine all the comments together.
Propagate Ratings to Hash Dupes. This option will copy ratings amongst hash duplicate sets. You can select to choose the rating from the highest rated photo or lowest rated photo.
With this option, you point ADD to the location on your file system where the Aperture library resides. By doing so, ADD will have direct read only access to the library and thus can perform hashing/comparison operations much more quickly.