The top one is the drive as a whole, the item(s) listed below it are the partitions contained within that drive. In your case there's only one, but if you ever have a drive with 2+ partitions on it, they will both show up as indented under the main drive icon.
What is the difference between the two icons and information for the same drive in the left hand side of the panel?
There is one shown above the other. The lower is shown indented and is the one displayed on the desktop.
Does one represent the hardware version and another a soft or logic version? Is performing a repair disk or permission enough on one and if so which one?
OSX 10.5.8, PPC G5 2.0, 5.5 GB RAM

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