Everyone has duplicates on their computers. I know I've downloaded my phone a few times without organizing the photos and a few duplicates end up on iPhoto. To be more exact, almost 15gb end up as duplicates. I've used Clean My Mac for a few years, an app that cleans out and makes space for my computer. The people behind the app I trust came out with Gemini, a desktop app that find duplicates for you and allows you to delete them. Before I paid extra storage for cloud drives, I decided to give Gemini a try. As of this date posted, Gemini goes for $9.99, but that's cheaper than buying a new hard drive or upgrading to a cloud space to house the same files. If you do end up wanting to delete both files, there's a warning that pops up. I've used it to clean photos, my music library, files in Pages, and even screenshots. This is why Gemini is one of my favorite apps right now. Try it for yourself here.