Vodka, soda water (water with bubbles, don't know if it's called the same in the US?), dash of orange juice = Tweedledum.
Vodka, soda water, dash of apple juice (or some other juice) = Tweedledee
So you'd have not one but TWO cocktails :D
ETA I don't know how the dash of juice would taste (I would normally just have vodka, soda water and a piece of fresh lime or lemon). If you have Aperol, you could do a dash of that instead for one of them.