I have a 50,000 photos, such is the ease of taking digital snaps spread across a few family members. 

The google drive (photo) sync app uploaded all of these photos to google photo which is just great. 

I reinstalled my OS and google drive is uploading all 50,000 photos again. Not sure if it is making duplicates in google cloud yet :)

I cannot find any info about any way to avoid this, seems like there should be a better solution for OS reinstalls,  such as 'adopting' a previous install (like crashplan does). 

Just curious if anyone has gone through the same hassle.