Wasn't Cleopatra considered a great beauty - one of the reasons why both Caesar and Marc Antony fell for her? So why would Angelina Jolie be considered too beautiful to play her?
True, we've no lifelike portraits of her to see what she really looked like, only a bust and statues made in the traditional Egyptian way which makes everybody, male or female, pharoah or slave, look pretty much the same as everybody else, but there must have been some reason for the tales of her great beauty to have arisen.
Funnily enough, she wasn't considered a great beauty at the time. Contemporary descriptions attest to the fact that she wasn't beautiful but was possessed of great charm, intelligence, wit and a honeyed speaking voice. Of course, such charisma is difficult to portray on the screen in the confines of a two-hour movie, so I don't mind them casting a beauty to get across her allure. Some of the artwork depicting her (especially coins) show her to be quite ugly with a very hooked nose and mannish profile, but who's to say how accurate they are. I reckon they'll show her as the traditional 'Egyptian' female, though. In reality she only wore Egyptian garb for ceremonial purposes and otherwise is assumed to have dressed and looked like her fellow Hellenistic contemporaries (which the bust shows).