如何使用嵌套循环仅将名称中有重复字符串的文件复制到任何文件夹？

import os
import shutil

def copy_files_with_duplicate_strings(source_folder, destination_folder):
    files = os.listdir(source_folder)

    for i in range(len(files)):
        file1 = files[i]
        string1 = extract_string(file1)

        for j in range(i+1, len(files)):
            file2 = files[j]
            string2 = extract_string(file2)

            if string1 == string2:
                source_path = os.path.join(source_folder, file1)
                destination_path = os.path.join(destination_folder, file1)
                shutil.copy(source_path, destination_path)
                break

def extract_string(filename):
    # 提取文件名中的字符串，可以根据具体的命名规则进行实现
    # 这里仅作示例，假设文件名中的字符串位于括号内
    start_index = filename.find('(')
    end_index = filename.find(')')
    if start_index != -1 and end_index != -1:
        return filename[start_index+1:end_index]
    else:
        return ""

# 示例用法
source_folder = "/path/to/source/folder"
destination_folder = "/path/to/destination/folder"
copy_files_with_duplicate_strings(source_folder, destination_folder)