A: If Double Vision is in play with Draw 1, making players Draw 2 instead, and then someone plays Draw 2, the draw rule has gone from “Draw 2” to “Draw 2” so no additional cards should be drawn.

Here is another example: when going from Draw 1 + Double Vision (= Draw 2) to Draw 4, the player has already drawn 2 on their turn, and would need to draw 2 more to make their total drawn 4.