20 centavos Rays on reverse variety

Cuba 1920 20 Centavos “RAYS ON REVERSE” Variety or Mint Error?

1920 20C RAYS ON REVERSE variety
1920 20C RAYS ON REVERSE variety
Stack’s March 2008 Coin Galleries
CUBA. Republic. 20 Centavos, 1920. Arms of the Republic. Rv. Star in rays. KM 13.2. Gleaming cartwheel silver displays a wealth of peripheral gold. MS-63 (ANACS).
Update 1
Obverse design features overlayed on both the obverse and the reverse showing perfect overlap of the obverse star and rays and the reverse rays
The overlay shows relative position of dies when the die clash occurred,
courtesy of Ricardo Lopez. 
Update 2
Now for Sale!
Note the very prominent RAYS ON REVERSE!