Two External WD Passaport not recognized simultaneously

I have two external hard drive WD Passport 0748: a black and a silver one.

If I conect the black one first and then the silver one, the black one will be showed on Windows Explorer and the silver one won’t.

If I conect the silver one first and then the black one, the silver one will be showed on Windows Explorer and the black one won’t.

My Windows is 8.1 with two USB 3.0 (but the same problem occurs on my notebook Windows 7 SP1 with two USB 2.0 and one SATA).

So the problem is not on the cables, nor on the physical bus, nor on the external drives, since they are being recognized individually.

The real problem is to try to use them at the same time.

Both external drives are recognized as conected, but there is a difference at the devices manager. The difference is the property device. The one that is showed on WIndows Explorer has the properties:

  • Name: USB Mass Storage Device | Type: Universal Serial Bus controllers
  • Name: WD My Passport 0748 USB Device | Type: Disk drivers
  • Name: WD Passaport Black | Type: Portable Devices
  • Name: WD SES Device | WD Drive Management devices

The other one has the properties:

  • Name: USB Mass Storage Device | Type: Universal Serial Bus controllers
  • Name: WD My Passport 0748 USB Device | Type: Disk drivers
  • Name: WD SES Device | WD Drive Management devices

Can anyone help me?

See if this helps  https://wdc.custhelp.com/app/answers/detail/a_id/6571 it might be a windows problem.

Joe