This is CocoRosie. I really like their music. I think. Listen to the whole song before you judge. The duo was formed by sisters Sierra Rose Casady ("Rosie") and Bianca Leilani Casady ("Coco") in 2003. Their music is strangely beautiful, compelling...and for some reason I can only write in short, incomplete sentences when listening. Anyway, the link above gives their WIKI bio which provides some insight into why their music is so different. It's an interesting life they've lived to this point...