At first, I think 2 hands at $70 will give me the same standard deviation (sd) as 1 hand at $100, since (2*70)/2^.5= 100, but upon further thought, this is not right because these two hands are not independent, since we both face the same dealer hand.

So what value of each of my 2 hands will give me the same sd?

Also, if I am playing heads up, I will bet more money at 1 hand of $100 than 2 hands of $70. (For example, if there are 6 hands left in the shoe, I bet 3 hands at $100 ($300) or 4 hands at $70 ($280)) So the goal of getting more EV is negated.