These were originally made in the 1960's during the Civil War centennial, and were to be used as novelty items. Some are still being manufactured today for the same novelty purpose as well as a Southern heritage preservation item to attach to letters, packages, etc.
But as with many good intentioned things, they make their way into the wrong hands. And, thus, the reproductions have hit the market and are being sold as "genuine."
As with the reproduction stamps of the 1960's, the paper and glue is getting a nice light "brownish" patina (darkening of the paper) which can be very convincing to the beginning collector.
On REAL stamps, be sure to look for "crude" graphics and lettering, uneven glue on back (of unused stamps), old stamp paper stock, and signs of a strike-cancellation mark on some "used" stamps.
Extreme caution is advised when purchasing Confederate postage stamps. Novelty reproductions (such as these) will almost always be in MINT condition complete with full slick glue, sharp lettering and graphics, very crisp, clean and a "sharp as a tack" newness feel to them.