I don't have this issue of duplicate photos on Google photos after setting up the Note 10. How did you set up note 10? By any chance you copied over the photos from your last device to Note 10 and then Google photos thought to back them up as well once you restored Note 10.
I have had similar issue on my iPhone when my photos were backed up to iCloud library. When I set up new iPhone, iCloud photos/library used to download photos on the new phone and then Google photos thought they were new photos on device and started backing them again. I stopped using iCloud library in favor of only Google photos and OneDrive on all devices (Android/iOS) after which I haven't had much issue.