def caseless_uniq(un_uniqed_files):
    """
    Given a list, return a list of unique strings, and a list of duplicates.
    This is a caseless comparison, so 'Test' and 'test' are considered duplicates.
    """
    lower_files = []  # Use this to allow for easy use of the 'in' keyword
    unique_files = []  # Guaranteed case insensitive unique
    filtered = []  # any duplicates from the input

    for aFile in un_uniqed_files:
        if aFile.lower() in lower_files:
            filtered.append(aFile)
        else:
            unique_files.append(aFile)
            lower_files.append(aFile.lower())
    return (unique_files, filtered)