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#41
Yes, if you want to keep two identical backups, which you should, you would need two. The backup drive should be at least as large as the drive it is backing up.
A docking station allows you to plug in a bare internal type HDD into it and connect it to the computer via either USB or e-SATA (the one you listed gives you a choice; choices are a good thing). I prefer using bare HDDs in a docking station (I have one built into my computer) because they take up less room in storage and the bare internal type drives are usually better quality than the ones used in external HDDs.