Two My Passport 2Tb in a same pc not work!

I connect 2 WD My Passport 2Tb via usb 3.0 in my HP Envy 15 3040, and only work one of this.

OS is W7 64.

It says " Two discs with same digital firm" or something like this…

Help me!

Thanks in advance

Robert

It’s a Windows thing See post 11 it explains how to fix it   http://community.wdc.com/t5/My-Passport-for-PC/Copy-files-from-one-drive-to-another/m-p/277504/highlight/false#M7587 

Joe