AWS签名URL是用于生成带有签名的URL，以便访问AWS S3存储桶中的对象。它主要用于授权和加密目的，并不直接用于检查重复图片。

要检查重复图片，您可以使用AWS S3的其他功能和API。以下是一个示例代码，演示如何使用AWS SDK for Java来检查AWS S3存储桶中的重复图片。

首先，确保您已经安装了AWS SDK for Java并配置了您的AWS凭证。

import com.amazonaws.AmazonClientException;
import com.amazonaws.AmazonServiceException;
import com.amazonaws.auth.profile.ProfileCredentialsProvider;
import com.amazonaws.regions.Region;
import com.amazonaws.regions.Regions;
import com.amazonaws.services.s3.AmazonS3;
import com.amazonaws.services.s3.AmazonS3Client;
import com.amazonaws.services.s3.model.ListObjectsRequest;
import com.amazonaws.services.s3.model.ObjectListing;
import com.amazonaws.services.s3.model.S3ObjectSummary;

public class CheckDuplicateImages {

    public static void main(String[] args) {
        String bucketName = "your-bucket-name";
        String folderName = "your-folder-name";

        AmazonS3 s3client = new AmazonS3Client(new ProfileCredentialsProvider());
        s3client.setRegion(Region.getRegion(Regions.DEFAULT_REGION));

        try {
            ObjectListing objectListing = s3client.listObjects(new ListObjectsRequest()
                    .withBucketName(bucketName)
                    .withPrefix(folderName + "/"));

            for (S3ObjectSummary objectSummary : objectListing.getObjectSummaries()) {
                // 获取对象的MD5摘要
                String md5 = s3client.getObjectMetadata(bucketName, objectSummary.getKey()).getETag();

                // 通过比较MD5摘要来检查重复图片
                // 如果两个对象的MD5摘要相同，则它们是重复的
                // 可以采取相应的操作，如删除其中一个对象
                System.out.println("Object Key: " + objectSummary.getKey());
                System.out.println("MD5: " + md5);
            }
        } catch (AmazonServiceException ase) {
            System.out.println("Caught an AmazonServiceException, which means your request made it to Amazon S3, but was rejected with an error response for some reason.");
            System.out.println("Error Message:    " + ase.getMessage());
            System.out.println("HTTP Status Code: " + ase.getStatusCode());
            System.out.println("AWS Error Code:   " + ase.getErrorCode());
            System.out.println("Error Type:       " + ase.getErrorType());
            System.out.println("Request ID:       " + ase.getRequestId());
        } catch (AmazonClientException ace) {
            System.out.println("Caught an AmazonClientException, which means the client encountered an internal error while trying to communicate with S3, such as not being able to access the network.");
            System.out.println("Error Message: " + ace.getMessage());
        }
    }
}

请将your-bucket-name替换为您的存储桶名称，将your-folder-name替换为您要检查的文件夹路径。

这段代码将列出指定存储桶中指定文件夹下的所有对象，并打印出它们的键和MD5摘要。您可以根据MD5摘要来检查重复图片。如果两个对象的MD5摘要相同，则它们是重复的。