Aspose.PDF for .NET 多重签名 - 除最后一个签名外，所有签名均无效

如何解决Aspose.PDF for .NET 多重签名 - 除最后一个签名外，所有签名均无效

我使用 Aspose.PDF for .NET 对带有多个签名的 PDF 文件进行签名。当我通过 Adob​​e Reader 打开文件时，所有签名都显示：“自签名应用以来，文档已被更改或损坏”，除了最后一个.我该怎么办？谢谢！ 这是我基于官方示例的代码

https://docs.aspose.com/pdf/net/improved-and-flexible-pdf-signing-mechanism/

            string file = "E:\\Temp\\0.pdf";
            // Create FormEditor object
            FormEditor editor = new FormEditor();
            editor.BindPdf(file);
            // Add signature fields
            editor.AddField(FieldType.Signature,"1",1,3149,1390,3324,1477);
            editor.AddField(FieldType.Signature,"2",3164,1302,3309,1389);
            // Save the form
            file = "E:\\Temp\\1.pdf";
            editor.Save(file);

            for (int i = 1; i < 3; i++)
            {
                string signImageFile = "";
                PKCS7Detached pkcs = null;
                PdfFileSignature pdfSign = new PdfFileSignature();
                System.Drawing.Rectangle signRect = new System.Drawing.Rectangle();

                if (i == 1)
                {
                    pkcs = new PKCS7Detached("E:\\Sign\\1.p12","111111");
                    signImageFile = "E:\\Sign\\1.png";
                    signRect = new System.Drawing.Rectangle(3149,175,87);
                }
                else if (i == 2)
                {
                    pkcs = new PKCS7Detached("E:\\Sign\\2.p12","222222");
                    signImageFile = "E:\\Sign\\2.png";
                    signRect = new System.Drawing.Rectangle(3164,145,87);
                }
                pkcs.ShowProperties = false;

                pdfSign.BindPdf(file);
                pdfSign.Sign(i.ToString(),"",pkcs);
                pdfSign.SignatureAppearance = signImageFile;
                file = Path.Combine("E:\\Temp",(i + 1).ToString() + ".pdf");
                pdfSign.Save(file);
                pdfSign.Close();
            }