7zip has trouble compressing a directory on windows if it contains two filenames which differ only in capitalization... This script will find problematic file pairs and delete conflicts.

duplicate_file_resolution.py

import os
import sys

def main():
	filedict = {}
	for path, dirs, files in os.walk(sys.argv[1]):
		for f in files:
			full_path = os.path.join(path, f)
			l = full_path.lower()
			if l not in filedict:
				filedict[l] = [full_path]
			else:
				print("duplicate:")
				print("{}".format(full_path))
				print("{}".format(filedict[l][-1]))
				filedict[l].append(full_path)
	while True:
		ans = input("Resolve filename collisions? [y/n] ")
		if ans == "y":
			print("resolving collisions...")
			for key, entry in filedict.items():
				for f in entry[1:]:
					os.remove(f)
			print("done")
			break
		elif ans == "n":
			print("exiting")
			break

main()