The info in Don's chart doesn't take into consideration practical betting which would likely have you bet at 75% of your initial bet. This would even things up. But then you have to consider that the dealer will not have to play his hand out more often when you are playing one spot and that tilts things back to favoring one hand. The differences are minimal so while there is a winner, playing one hand heads up, it really makes little difference. Just do what you like better.

If you do wish to split hairs take into account your actual bets you would make. If you don't want to bet a rainbow stack to speed up the game which would result in more money per 100 rounds than Don's chart implies and used Don's example of 1 hand of $500 and 2 hands of $365, instead you would bet 1 hand of $500 or 2 hands of $375. That would not change the 1 hand total bet of $50,000 but would increase the total bet on the two card hand to $50,250 and be the better choice. But that doesn't factor in the increased number of rounds the dealer didn't have to play out his hand because you got a BJ or busted on one hand, which would narrow that gap.

A practical bet may have been rounded down to the $350 even though that is not the closest $25 increment or rounded down with other bets because the larger increment of chips you are betting was not closer to the 73% bet. That would make the lead for 1 hand be even more.

So you might want to look at how playing 2 hands the way you would in a casino affects things rather than what computer optimal says. Just remember there is still a cost in RoR to be factored in when your practical bet has you stray from the computer bet that has the same RoR for 1 spot and 2 spots. If you play to a high RoR this may be the most important factor to consider. If your RoR is essentially 0 then the RoR change is meaningless.