I think I read this 3-4 years ago, maybe as an ebook. The bit that I remember is, I think, not even the main plot, but it's what's sticking in my head. The protagonist is a female, teenage I think, in a "10-20 years into the future" dystopia. Her family is poor, not certain who's actually in the family except her and her sister. Her sister is very attractive, but can't showcase it due to their poverty, plus there's a famous movie star that looks a lot like her, so everyone assumes that she's trying to copy the movie star's looks. Meanwhile, the protagonist is convinced that her sister is the one being copied. Somewhere near the end of the book, she infiltrates a huge skyscraper that the movie star lives in, looking for answers. What she finds is a functional, clean, but completely deserted, apartment, with no evidence that the movie star lives there. I forget how the revelation happens, maybe accidentally tripping a system, but it turns out that the movie star doesn't exist as anything but a hologram, which indeed is programmed with the looks and style of the protagonist's sister. And... I don't really remember what they do after that.
I think it was meant as a Young Adult book. The only bit of violence I remember was a scene earlier in the book where the girl gets approached by some boys on the street at night, who make vague threats until they get chased off by a random boy who shows up, beats them up, and then... I think smashes a nearby camera and gives the memory card to her if she ever needs to use it as evidence? My memory is kind of vague, but I think maybe he's who she learned the building infiltration skills from.