Early 2011 A1286 15"
Ok great, I thought that maybe it was an optical drive. Should be good to go.The early 2011 MBP only comes with one internal HDD, UNLESS someone removed the optical drive and install another storage drive in the optical drive location after it was purchased. There was no option from Apple for 2 internal HDDs.
If you do have 2 internal drives then I would assume they have data you want and therefore should be backed up.
EDIT: I see you added a picture to your post since I started my post. The picture shows your optical drive where it should be (top left of picture), so you only have the 1 HDD to copy.