How can I delete duplicate images from my hard drive?

Episode 1166 (2:11:16)

Mark from Costa Mesa, CA

Adobe Lightroom has de-duping features, as does Picasa. But Leo is nervous about deleting images automatically. It's far better to just have a huge hard drive and then use Lightroom to organize his files by date. Then he can de-dupe down the road, and keep all of his RAW files. He can convert to Adobe's DNG format because it's a universal format that will always be readable.

The Chatroom says Graphic Converter on the Mac can do it. Photo Sweeper also does this.