The latest version doesn't work with the new Mac Photo, at least not on my system. That is, Duplicate Annihilator identifies duplicates but doesn't mark all (or even most) them, so there's no way to remove the duplicates. When I reported the problem, Brattoo was very responsive and pleasant, but until the problem is fixed I wouldn't recommend the software. Here's their reply, "This is an internal Photos error which seems to occur now and then, we have reported it to Apple and hopefully it will be resolved soon. It does not happen to every Photos library but some customers have reported it. Sometimes it happens to all photos and sometimes to only a few. We are trying to pinpoint when and why it happens but unfortunately we have not been able to get this error in our labs."