It is hard to tell if it is an 'original' third of a 1947 mint set. Can you post a picture of the edge of the cardboard? Also, how thick is it (measured with a caliper). I think that the 1947 cardboard is thicker than later years, but many 1947 mint sets have been made by putting 1947 coins in newer cardboards. Within each cardboard, there are two holes for each coin to show both the obverse and reverse. It looks like someone peeled the paper off the back of your holder to see the reverse sides as half the coins are flipped over.
I can tell you that the coins in the original old mint sets are quite high grade with good strikes, and usually grade well.
Unfortunately, my 1947 mint set is missing one cardboard, so please don't throw that away - PM me. The set I have was sent to a family member from the mint in 1947, but I have no idea how the one green cardboard became missing....