The moth streams stopped after Pippa exploded in popularity. Rie used her past account on Twitter for commissions and the like. Lia also had another Twitter handle where she would take pictures of her cosplay but that was killed off after the male voice actor groomer invaded her donothon.I haven't seen anyone use their alt to stream since Gen 2 came out, probably before that (when was moth/Owl girl's last stream?). I guess they could have unknown accounts though.
I don't know if anyone in Gen 3 would stream as their other self. Would be nice if Purin took off her cow wig and bell once in a while though.