Who on the 13th?

[Eisi]

MSQ 6.5 spoilers

I think they had to do it this way because if they had voiced Golbez it would have been obvious that the past one wasn't the same as the present one, since they are two different people and thus would have differing voices. (Even though it was already obvious to anyone paying attention, but up until 6.5 it was treated as a secret and in 6.5 it was treated as a surprising reveal).

Two birds one stone if you ask me! At least that would be genius imo. If that alone was the explanation it'd be pretty mid.