I discovered that I've been playing double deck wrong! There are a few parts of the 2D, DAS game that I've been getting wrong, according to the basic strategy generator on blackjackinfo.com. Here are the decisions I just discovered I was supposed to do:

4,4 vs. 5 = split
4,4 vs. 6 = split
6,6 vs. 7 = split
7,7 vs. 8 = split
A,7 vs. 2 = double

The pair of fours decision I've known to do in 6 deck games, but for some reason I thought it was a hit in double deck. But the 6,6 and the 7,7 decision really baffle me! I ran simulations on BJ PowerSim to see what difference it would make to follow or to not follow these decisions, and it didn't make much of a difference at all. Are these correct?