Searching for duplicate SWFs with Python

#!/usr/bin/python
import os
from sys import argv
from glob import glob
from hashlib import md5 as MD5

targetDirectory = "." if len(argv) < 2 else argv[1]

foundFiles = {}
for f in glob(os.path.join(targetDirectory, "*.swf")):
    if not os.path.isfile(f): continue

    fsize = os.path.getsize(f)

    if fsize in foundFiles:
        foundFiles[fsize].append(f)
    else:
        foundFiles[fsize] = [f]

duplicateFiles = {}
for size, files in foundFiles.items():
    if len(files) > 1:
        for f in files:
            data = open(f, "r").read()
            md5sum = MD5(data).hexdigest()

            if md5sum in duplicateFiles:
                duplicateFiles[md5sum].append(f)
            else:
                duplicateFiles[md5sum] = [f]

for md5sum, files in duplicateFiles.items():
    if len(files) > 1:
        print "Duplicates for MD5:", md5sum
        for f in files:
            print "  ", f