z2 = coll2.find({})
            count=0
            for i in z2:
                somehash = i["hashvalue"]  # so get the a hash value from the old hard drive to be compared against the new drive contents
                z1 = coll.find({ "hashvalue": somehash  }) # can we find the hash from drive 2 collection on the drive 1 collection ?
                print ('query count is ', z1.count())

                if z1.count() >0 :   # we did get a match so there is a duplicate
                    bool= True
                else:
                    bool = False   #  the image on drive 2 does not have a match on the new drive 1 (so inspect it later)

                coll2.update_one(
                    {'_id': i['_id']},
                    {
                        '$set': {'isdupe': bool}
                    }
                )