I think there's an argument for playing 18/13 7/4 in position 1 and 12/4 in position 2.

Note that 18/13 7/4 is better when your opponent enters and 12/4 is better when your opponent dances. This is true in both positions.

What I'm thinking is that in position 1, 18/13 7/4 is "good enough" on White's dances. Black can double and White has a tough take/pass decision. Maybe a pass already. So if you (essentially) win the dances either way, you want to maximize for White's entries.

In position 2, if you get away with 18/13 7/4, maybe the cube isn't that efficient (if you have one at all). In other words, White has an easy take. So you want to give yourself a better cube on the dances which means 12/4.