问为什么使用Win32_PrintJob/C#获得错误的N-Up打印总页数？

EN

string wql = "SELECT * FROM Win32_PrintJob";
ManagementObjectCollection mos;
Dictionary<uint,short> checkedJobs = new Dictionary<uint,short>();

while (true)
{
      Thread.Sleep(SleepTime);
      try
      {
           mos = new ManagementObjectSearcher(wql).Get();
           if (mos != null && mos.Count > 0)
           {
                foreach (ManagementObject mo in mos)
                {
                    if (mo != null)
                    {
                        uint jobId = ProcessJob(mo);
                        if (!checkedJobs.ContainsKey(jobId))
                            checkedJobs.Add(jobId, 0);
                        }
                    }                        
                }
                // ...
           }
      }