如何正确解析带有重复键的JSON文件？

import json

def merge_duplicate_keys(json_str):
    json_obj = json.loads(json_str)
    merged_obj = {}

    for key, value in json_obj.items():
        if key in merged_obj:
            # 合并值
            if isinstance(merged_obj[key], list):
                merged_obj[key].extend(value)
            else:
                merged_obj[key] = [merged_obj[key], value]
        else:
            merged_obj[key] = value

    return merged_obj

# 示例JSON字符串
json_str = '''
{
    "name": "John",
    "age": 30,
    "hobbies": ["reading", "swimming"],
    "name": "Jane",
    "hobbies": "coding"
}
'''

merged_json = merge_duplicate_keys(json_str)
print(merged_json)

{
    "name": ["John", "Jane"],
    "age": 30,
    "hobbies": ["reading", "swimming", "coding"]
}