This is definitely a concern, but depending on your state education is a distorted market. Where I grew up, 8-12 educators (even most private ones) had to have

This is definitely a concern, but depending on your state education is a distorted market. Where I grew up, 8-12 educators (even most private ones) had to have a teaching degree and a subject matter degree. As a result, pretty much all of them had either a subject Bachelor's and an advanced degree in teaching, or a teaching BS and a subject Masters. A double major would have been fine, but that's rare. The regulatory landscape had basically enforced teaching as a two-degree profession.