KitCam for iPhone, my favorite photo and video app by a mile, keeps a copy of your original photos even after you edit and apply lenses, film, and frames.
When you share one or more photos, tap the gear icon at the top of the share menu to choose between sharing the original (unedited) “master” or the “version,” your edited masterpiece.
As of version 1.6, this only works for photos, not videos. Regardless, KitCam is the best money you can spend in the App Store on shooting, editing, and organizing photos and videos.