Hello, and welcome to the forum
The short answer is, yes, that is a reprint from an unused plate, what is called an Altered Plate. Here's a version fo the story from another of my posts:
'Those are what are called Altered Plates. The original 5¢ stamp and a 1¢ picturing John C. Calhoun (#6,7 and 14, which was never issued) were designed and printed by De La Rue in London in 1862. By the next year it was necessary to raise the postal rate, so the Confederate Posties asked De La Rue to come up with a new set. As time was of the essence, it was decided to simply alter the plates (hence the name) from 1 to 2¢ and 5 to 10¢ respectively.
The plates were sent back to Richmond but were never used. Could be delivery was too slow (no Fedex). I have read a story where Mrs Davis disapproved of the portrait on these stamps because she though it made her husband look too much like that Lincoln guy. I've read of rumours during the war that Lincoln and Davis were actually related, simply because there was a slight physical resemblance.
So other stamps were designed (CSA#8 and #9) and the altered plates were filed away.'
So there it is.
The unused plates were rediscovered in the 1920s by August Dietz, considered to be the 'Father of Confederate Philately'. Dietz printed the new 2¢ stamp in emerald green. Here's my copy of the emerald green Calhoun from my collection.
Both plates were reprinted a number of times over the years after Mr Dietz's discovery. With varying degrees of quality.