When you attach two (or maybe more) external storage devices like the WD Passport on your Windows 7 machine and you notice that only one drive is working or currently visible on your WIndows Explorer, first DON’T PANIC!Chances are you’re having a so called HDD Signature Collision error which you can only be seen by looking at your Device Management console:
The quick fix on this is to simply right click-click the Offline disk and select Online. Your other external storage will become visible now on your Windows Explorer.
Sweet and simple solution.
Life & Technology 