Same Inductor, Different Laminations

My question is depicted below!
The inductor is used in a Boost regulator, working in CCM @15kHz. It has to handle a dc current of 100A and a small ripple of some 10~20A (15kHz). The regulator has an input voltage in the range of 220-550 VDC and an output of 770 VDC. Two identical inductors are used, each having an inductance of 850uH. Regulator is designed to give 20kW of power.

No good reason that I can think of.

final exam question?

No, not a final exam. This inductor has been implemented in an Italian UPS and has worked so well all the time, except nowadays!