for years I've been using Dropbox's "camera uploads" feature to upload my iPhone's photos. I also have a separate location on dropbox with a TON of photos from other cameras/sources in a random folder called "photos". recently I thought I would be make my "photos" folder sync local to my Mac, use Apple Photos to to catalog all of it. unfortunately, this causes dropbox to see ALL the photos, to then populate my iPhone and upload them all back into "camera uploads" -- now I have tens of thousands of duplicates, and every time dropbox launches it continuously uploads a ton of duplicate pictures.