I just bought two My Book 4 TB drives but Windows 8.1 will not recognize both drives if they are both connected at the same time. They are both recognized if I only connect one drive but when I try to connect both drives only one is recognized. Disk Managment does not show both drives and only one drive is assigned a drive letter. I have tried to change the drive letter to a different drive letter but that doesn’t help either. Running a Dell XPS 8300 desktop computer.
This is a well-known Microsoft Windows issue known as Signature Collision. Please visit the following link for additional information and possible resolution steps:
Such an easy solution to my problem. Thank you very much for pointing me in the right direction!