|I don't understand it since I also have two identical WD Elements drives (though mine are both designated "HDD 1021" in "Safely Remove Hardware") and yet I have no conflict at all when I have them plugged in at the same time. Windows just gives them both a different drive letter and I have no problem at all.|
If you bought them both at the same time (which I did not) you probably plugged them both in together to your PC for the first time as well. I suggest you unplug them both.
Now plug only one of them in and wait for Windows to recognise it, then check that you see it with a drive letter in Windows Explorer.
Then, and only then, plug the second one in and Windows should assign a different letter to it automatically.
Those two drive letters will then be remembered and assigned automatically by Windows for that specific drive each time you plug it in.