Secondary external hard disk not detected

I am trying to transfer data from one external hard disk to other. However, when one is connected, another one doesn't connect, and vice-versa. It doesn't even show up on "fdisk -l". Nautilus does not show it either.

Has anyone faced similar problem? Is there any way to mount the second external hard disk?

OS : Ubuntu 16.04 LTS (latest updated), Laptop : Lenovo Z Ideapad

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