I have the same question. It use to be automatically after you added a contact if the name matched it would add the photo to your contacts. I miss this feature. I also mis Samsung Photo back up. I never had problems with duplicates. Samsung Had the Best, of the best. Please bring it back!
This method is for the Google Contacts app, if you're using that. First Open the Google Contacts app> next navigate to the contact you're looking to add a photo to> Next tap the pencil icon at the top right corner (the edit contact button) > From here you can add a photo to that contact individually at the very top. This will save to your Google Contacts list.
If you're using the Samsung Contacts app, the method will be similar only the edit contact button will be at the bottom of your list and you tap on the circle icon of your contact to add a photo to that contact. Note that this will only save for your contacts you're saving in the Samsung Contacts app and not for Google Contacts.
