在c#中复制文件时检查是否有重复的文件名

我想将文件复制到一个目录并重命名为特定的格式。但是如果文件名已经存在，它应该在文件扩展名之前附加{1}，{2}或{3}。

我的代码重命名并复制了文件，并将其命名为我想要的格式，例如filename.pdf，当它检查是否重复时，它将其重命名为filename.pdf。但是当它再次尝试复制时，它给出了一个错误"文件已经存在"，但我希望它已将其命名为filename02.pdf。

有人能帮我一下吗?

这是我目前为止写的代码。

    {
        string fileSource, filesToCopy, target, nextTarget;
        string sourceDir = @"C:'HCP_PDFs";            
        string destinationDir = @"C:'RenamedHcpPdfs";
        DirectoryInfo di = new DirectoryInfo(destinationDir);
        // create the directory if it dosnt exist
        if (!Directory.Exists(destinationDir))
        {
            Directory.CreateDirectory(destinationDir);
        }
        foreach (string myFiles in lstBoxFilenames.Items)
        {
            filesToCopy = myFiles;
            fileSource = Path.Combine(sourceDir, filesToCopy);         
            //Extract only HCP Name by splitting , removing file Extension and removing HCP ID 
            string hcp = filesToCopy.Split('_')[0];
            string hcpCd = filesToCopy.Split('_')[1];
            string hcpID = filesToCopy.Split('_')[2];
            string hcpName = String.Format((filesToCopy.Split('_')[3]).Replace(".pdf", ""));           
            //combine the HCP ID, HCP name and date                                                
            target = Path.Combine(destinationDir, hcp + "{" + hcpCd + "~" + hcpID + "}" + hcpName + "{2013_03_14}" + ".pdf");
            // if file exists in directory then rename and increment filename by 1
            int i = +1 ;
            nextTarget = Path.Combine(destinationDir, hcp + "{" + hcpCd + "~" + hcpID + "}" + hcpName + "{2013_03_14}" + i + ".pdf");
            if (File.Exists(target))
            {
                File.Copy(fileSource, nextTarget);
                break;
            }
            //if file does not exist, rename              
            else
            {
                File.Copy(fileSource, target);
            }          
        }            
    }

string target = Path.Combine(destinationDir, hcp + "{" + hcpCd + "~" + hcpID + "}" + hcpName + "{2013_03_14}.pdf");
while(File.Exists(target))
        {
            i++;
            target = Path.Combine(destinationDir, hcp + "{" + hcpCd + "~" + hcpID + "}" + hcpName + "{2013_03_14}" + i + ".pdf");
        }
File.Copy(fileSource, target);
break;