This has reminded me what happened on the other side of the Alps in the elections of 1929. People received two envelopes. One with the national flag on the inside and a white one. They left inside the booth the one they didn't like and gave the other one back to the scrutineers. The outside was almost the same but the color inside was visible from the outside [1] Guess the result. Hint: almost 99% to 1%.
[1] https://en.wikipedia.org/wiki/1929_Italian_general_election
[2] https://it.wikipedia.org/wiki/Elezioni_politiche_in_Italia_d... for more details and pictures of the cards inside out.