How to keep iPhone photos synced on Mac?
To solve the issue with Photos.app and duplicate photos appearing on your iPhone, follow these steps:


Connect your iPhone to your Mac using a USB cable
Open Photos.app
Select 'Delete items'


This will delete your photos after they've been imported in Photos.app. This will prevent any duplicate photos from appearing in Photos.app on your iPhone.


On you Mac you can set up Image Capture.app so it a) copies all images/videos on your iPhone and b) deletes all images/videos afterwards. The following instructions work without Photos.app.

Step 1.

Make sure to disable Settings > Photos > iCloud Photo Library. This will make your iPhone appear as a 'Camera' so Image Capture.app is able to copy/delete media in your iPhone.

Step 2

To sync your photos in iTunes specify the folder your iPhone's media gets copied to.