A one-sided strike mint error occurs when two blanks enter the coining press at the same time. As a result, two coins are produced with one side unstruck. This side is not perfectly flat, but shows a deformation corresponding to the design of the die that struck it through the second blank. This error is quite rare, since it is rejected at the mint.
One-sided imprint 1 Kopeck 1911.
SPB (Saint Petersburg Mint).
