Deleting Duplicates on Aperture

try ApertureExpert (http://www.apertureexpert.com). they have a forum and someone with more knowledge of A3 may be able to help. If you get an answer, let us know! good luck.

Only with additional software AFAIK.
http://brattoo.com/propaganda/#aperture here is one that is on the rather cheap side.

Tried the software above. It did pretty good flagging the duplicates, but it's not 100% right, which makes for a very slow process of validating if a picture really is a duplicate. But all in all, that software was great to find obviously duplicate events, etc.