I think she only has an official page for that matter. I doubt that she maintains an actual facebook account, let alone a twitter account. I've known some singers that let their own pr team do the tweets for them too.
This is kind of a special case since she's a well-known singer, there's going to be a lot of fake profiles out there or even trying hard copycats that can mislead a lot of people into going to their page or content. For this situation, I think that the only thing that separates the real account from the fakes are the exclusive content that will most likely be seen first on the official page.
I've read a bit about those fake profiles and I'd just like to share it to all. http://darktips.com/11-tips-to-identify ... n-facebook
It would be good to be aware and be well-informed of these as well.