"Vous m'avez considérée comme une amie."
Translation:You have considered me as a friend.
To me these don't mean the same thing at all. "You consider me a friend" means you consider me to be a friend, whereas "you consider me as a friend" sounds like you're holding friendship auditions and I'm under consideration for the position. Or else you're considering me (ie. actively thinking about me) specifically as relates to my status as your friend.
I would not consider the latter good English grammar if your meaning was the former.
Is this some weird regionalization? What does the French sentence really mean?