how do I get an app that deletes duplicates of photos

Hi cathy1205,

You don't need to download an app to do this, you can delete duplicate photos within the Photos app on your iPhone. Here's a video from Apple Support on how to do this: https://www.youtube.com/watch?v=rVZGryGESMA

If you'd prefer to learn by reading, here's an article from Apple Support: Find and delete duplicate photos and videos on iPhone - Apple Support

Hope this helps!

-Dallen