I’m pretty sure they do double Martin 🙂 At first jump the first cube goes into 2. Then at next jump those 2 go into 4. Then at next jump those 4 go into 8 and so on … 🙂
But you’re right it might be harder to see due to the animations stacking. Let’s see if I can add a frame from when there are 2 cubes jumping.

4 total 🙂
Edit: Do you think by making the vertices another color (black) in addition to offsetting the cubes would help?