Something you can play around with – and you will need to experiment to figure out what is best for you – is the angle of the dumbbell on the shoulder. This is going to be an individual thing both because of differing limb length and geometry.
In both of the above cases the head of the dumbbell meets the movement standard, but we can play with the angle the dumbbell is held.
For me, using the top example position, the dumbbells are more stable which will keep the lunges consistent, but I can feel more pressure on my biceps and lats, which could affect the T2b and bar muscle-ups.
In the bottom example I feel less pressure in the biceps and Lats because more of the dumbbell is supported by resting the weight on the shoulders. This could help the t2b and bar muscle-ups BUT the lunges were more unstable. Getting no repped on a lunge sucks in this workout because you have to go back a five foot increment.
Again, this isn’t how to “crack the code” of this workout and secret to winning this work out. It’s just a thing. Play with it, experiment, and use what you’re most comfortable with.