First version | Python Fiddle

#! /usr/bin/python3

import sys, hashlib, os

call_path = sys.argv[1]

files = []      # (hash, path)

def parse(path):
    global files
    for f in os.listdir(path):
        fpath = os.path.join(path, f)
        if f.startswith('.') or f.startswith('~'):
            continue
        elif os.path.islink(fpath):
            continue
        elif os.path.isdir(fpath):
            parse(fpath)
        else:
            with open(fpath, mode='rb') as file:
                hasher = hashlib.sha512()
                while True:
                    buf = file.read(10000)
                    if not buf:
                        break
                    hasher.update(buf)
                files.append((hasher.hexdigest(),
                              os.path.relpath(fpath, call_path)))

parse(call_path)

files.sort(key=lambda t: t[0])      # sort by hash

length = len(files)
i = 0
while i < length:
    hash = files[i][0]
    j = i + 1
    if j >= length:
        break
    while files[j][0] == hash:
        j = j + 1
    if i + 1 < j:
        print( ':'.join(t[1] for t in files[i:j]) )
    i = j

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