1951 Matte Or Satin Finish Proof Dime?

Hello all. I have had for some years this 1951 proof dime that does not appear to be made normally. It lacks its mirrors. It appears satin or roman finished. However, As coin was struck with slightly incorrect die pressure, it bows toward the rev. at middle of coin and has some mirror at coin center in that pushed area. Coin has some die wipe. Baffles all my dealer friends and cannot find info. Question? Anything known about the mint experimenting in early fifties with Roman, Satin or Matte finishes? It appears real, as a proof, and has not been whizzed. Will post pics soon. Thanx,.. Gusp