Rabbit, I understan where you are coming from. This is one area where the code can be read multiple ways. Last year, the IAEA (the Inspectors' group) asked three real experts- and got four distinct answers!
Look through the proposals to the 2008 NEC. Several attempts are being made to clear this mess up. They also address Larry's point.
Larry, as I see it, if you use #6, then you may consider the second rod (if you must) in attaining the 25 ohm requirement. If you don't you can't. A pretty slim distinction, but that's the way the code seems to work it out.
