I've set my iOS camera uploads to add only new photos, but it's trying to re-upload everything.

I'm back - I tried to research but I can't be sure that iCloud is re-uploading to my Photos app as , nor can I figure out what to do about that. So I just tried a work around, but I don't think it worked. I can see the last photos that were backed up to my Dropbox, so I know where it stopped. So I tried to save new photos taken since then into an Album in my Photos app, and then in the Dropbox app, Camera Uploads, I selected to Upland from [that new album], and turned on camera uploads. But Dropbox seemed to be searching thousands of photos in my Photos app, not just that album. Is it because it's an album instead of a folder? It allowed me to select it so that was confusing. But if it needs to be in a folder, I can do that. Thank you so much for your advice.