Connect a second My Book 3T and computer won't recognize both together

Hi,

I’ve just purchased a second my book 3T. I already have one, same model.

When i connect them both only one is recognized.

Tried to change the volume letter but  the change changes both drives’ letter (can’t assign a different letter for each one)

Searched the wed and saw other people with the same problem.

As you can see it gives them both the drive letter l: although one is empty and the other full and they have different names

Anyone got an Idea?

Attached are the two constellations of the drive

es:

ok found the solution:

http://community.wdc.com/t5/External-Drives-for-PC/2-1TB-Passports-only-recognises-1/m-p/510822