How to remove duplicate photos in Google Photo

I used to sync my photos to Drive as well as to Google+. Now that the two have been merged, I see lots and lots of duplicates in the new Google Photo app. Unfortunately some of the photos were Drive only while others were in Google+ only and yet others in both... Short of going through all 16k++ photos in the new app what are my options? I know that I could use Picasa, but again I'll have to download all pictures first.