Actually I just listened to the original studio recording of Poppy´s "cover", and she does sound A LOT like the original TATU vocals. Still, these vocals are playing in this show, she´s just singing on top of it.
@Devin Kind Yeah, you were a littel all over the place in your first comment. But it seems we reached a verdict, the back studio track is playing throughout the whole song, and she is singing (humbly) on top of it; so it´s like her live vocals are working more like backing vocals, because without the pre recorded track it would be very weak and pitchy. But, like I said, it´s all about the like experience for the audience. I have been to concerts where it was all lipsyncin and they were great. ( I listen to many different types of music, hard electronics, metal, harcore.... But Britney Spears concerts usually rock, and it´s all lipsyncing, because it´s impossible, even for a good singer, to sing decently while dancing and performing like that). Honestly, I don´t give a fuck anymore, as long as the show is good.