Most of the explanations for this issue have to do with high precision of the betting ramp and the risk of ruin. They consider playing two hands as making one bet during one round.
However, consider the following thought process.
When you play one hand with another patron at the table, you play at x hands per hour.
What if that second player were you? Then you’d be playing 2x hands per hour.
If a clone of you with the same bankroll plays along with you, then you’re playing at twice the rate, although you now must have twice the initial bankroll.
If you and your clone were sharing the same bankroll, then your risk of ruin will increase.
However, because you’re playing at twice the rate, the fluctuation is smoother and you get to the expected outcome faster.
The rate of play (hands per hour) is important in smoothing out the curve.
Yes, you do extract more good cards (2/3 you vs 1/3 dealer) if playing two hands.
If a blackjack were to come out, you have twice the chance than the dealer.
Don’t you also have twice the chance of getting “bad” cards as well?
Yes, but bad card situations occur at low wagers.
Good card situations, such as getting an Ace and a ten, occur at high wagers.
At high negative counts, maybe your clone should pull back and wait for the count to rise.
Most people don’t have an inflexible bankroll and rarely bet *precise* Kelly. How do you go from $50 to $65? Two green chips with three red chips on top? No. You push out three green chips.
Most people do what’s comfortable to them.
Are you comfortable betting 2x$25 to 2x$350? Then work backwards to calculate your bankroll.
Would you prefer 2x$10 to 2x$100 instead? Again work backwards and calculate your bankroll.
The concept of bankroll is interesting in that it’s very, very subjective, and will vary based on your life situation. Bankroll isn’t an immobile monolith. Even whether your bankroll is replenishable or not is also subjective, and will also vary based on your life situation.
You can assess your comfort level and determine the min/max bet and bankroll at the same time.
And then choose to play at twice the rate as everyone else by playing two hands.