I forget it, but the account belongs to one of Yo's viewer (and donator).
Yo play with this account too, as a smurf for playing with other viewers/trying masterpieces against low-elo players.
Correct me if I'm wrong, didn't watch stream recently.
I thought that might be it but didn't want to assume - I remember hearing a similar story about other smurfs, such as one of Vivi's?