[sameasiteverwas]

The circuits simulated are valid, just that first picture is bad.

The serial boost converter is interesting, I've never seen that topology before - can anyone offer an explanation on how it works?

[ggeorgovassilis]

As I played around with the simulator I found that higher input voltages lead to better efficiency. My intuition is that as the first BC provides a higher input voltage to the 2nd BC, the 2nd BC operates with a higher efficiency.