Export功能 导致 页面显示很多非法字符，还可能页面显示两次

private void exportBinaryToExcel(byte[] bytes, string filename)
{
Response.AddHeader("Content-Disposition", "attachment; filename=" + filename);
Response.AddHeader("Content-Length", bytes.Length.ToString());
Response.ContentType = "application/octet-stream";
Response.BinaryWrite(bytes);
Response.Flush();
Response.End(); //这里的问题
}