如果您在AWS Forecast中尝试创建两个数据集组并使用相同的数据集ARN，则会遇到此错误。解决方法是为每个数据集组分配一个唯一的数据集ARN。您可以使用以下代码示例来创建数据集组并为其分配唯一的ARN：

import boto3

forecast = boto3.client('forecast')

# create dataset group 1 with unique dataset ARN
create_dataset_group_response = forecast.create_dataset_group(
    DatasetGroupName='my-dataset-group-1',
)
dataset_group_arn1 = create_dataset_group_response['DatasetGroupArn']

# create dataset group 2 with unique dataset ARN
create_dataset_group_response = forecast.create_dataset_group(
    DatasetGroupName='my-dataset-group-2',
)
dataset_group_arn2 = create_dataset_group_response['DatasetGroupArn']

# create dataset with unique ARN for dataset group 1
create_dataset_response = forecast.create_dataset(
    Domain='RETAIL',
    DatasetType='TARGET_TIME_SERIES',
    DatasetName='my-dataset1',
)
dataset_arn1 = create_dataset_response['DatasetArn']

# create dataset with unique ARN for dataset group 2
create_dataset_response = forecast.create_dataset(
    Domain='RETAIL',
    DatasetType='TARGET_TIME_SERIES',
    DatasetName='my-dataset2',
)
dataset_arn2 = create_dataset_response['DatasetArn']

# import data into each dataset
forecast.import_dataset(
    DatasetArn=dataset_arn1,
    DatasetImportJobName='my-dataset1-import',
    DataSource={
        'S3Config': {
            'Path': 's3://my-bucket/my-data.csv',
            'RoleArn': 'arn:aws:iam::123456789012:role/ForecastServiceRole',
        }
    },
)

forecast.import_dataset(
    DatasetArn=dataset_arn2,
    DatasetImportJobName='my-dataset2-import',
    DataSource={
        'S3Config': {
            'Path': 's3://my-bucket/my-data.csv',
            'RoleArn': 'arn:aws:iam::123456789012:role/ForecastServiceRole',
        }
    },
)