Problem: 2 WD 3TB element droves on 1 computer?

I request help concerning the following:

I have one 3TB Wd Element drive on which I have stored photos. I want to backup this to another 3 TB WD Element drive.

When I connect both to a PC (tried it on 3!) one on the WD Element drives is not recognised, obviously making data transfer impossible. (Tried the different USB ports!). Each of the WD element drives is recocgnised when connected to a PC on its own. Also when I connect either of the two WD element drives to a PC and also a different make external drive to this PC, both WD and the different make drive are recognised and I can happily copy files.

Any thoughts on how to get this working with the WD drives? 

Hello and welcome to the WD Community.

Sounds like the computer are detecting both drives as one and one of the units is getting offline. 

Goes to the disk management and enable the second drive from the there.

How to access Disk Management in Windows to manage hard drives