Most schools require a rec letter from a teacher and a counselor. If I have a counselor who also functioned as a teacher, can I ask her to write two letters, from the viewpoint of both posts, or do I ask her to write a single letter, inclusive of both viewpoints?
I would get two letters from two different people. Perhaps the counselor could include a paragraph about you as a student, but I’d get a second recommended to serve as the teacher LOR. IMO the more positive input colleges get from different sources the better.
I think it’s a mistake.
Your counselor is writing one letter of praise. Why waste the opportunity to have someone else add that they also think the world of you?