photos app imports duplicate pictures
I have macOS Sierra on iMac and iOS 11.4 on my iPhone 7Plus. I also have an iPad pro. I have photo stream on my phone/ipad and have my iMac set to download photos from the photo stream. I prefer not to have iCloud library set up because I have a HUGE NUMBER of photos and videos on my mac and do not want them on my phone and/or iPad. So, on occasion I will plug my phone into mac and transfer all photos and videos, not already downloaded, to my mac. However, now when I do this it will download photos and videos that have already been added to my photo library. Photos used to tell me how many photos that had not already been added, avoided having duplicates. I know I could just turn off photo stream downloads ... but really don't want to that, if possible.
Please help ... my Photos library is out of control
iMac (Retina 5K, 27-inch, Late 2014), iOS 11.4