Is it bad to have two letters of recommendation from teachers of the same subject area (i.e. two math teachers, two history teachers, etc.)?
In general, yes. Ideally you would have one rec from a humanities teacher and one from a science or math teacher.
Be sure to check each college’s website. Some have specifications as to who should provide recommendations.
It also depends on what you want to major in. If you’re clearly a history major it might not be terrible to have two history recs.
Generally, yes. However, if you took two history classes or two math classes junior year (i.e. both teachers taught you THIS year) then I don’t see why there would be a problem with it. Many people say “you need one from humanities and one from math/science” but I don’t find this to be useful advice, and neither does my GC.
Pick the two teachers that know you best. Mine happen to be a history teacher (who I’ve known since 6th grade) and an English teacher (I’ve written several extremely personal essays in that class that received high marks, & we often talked after class). If for you, that happens to be your AP Euro & APUSH teacher, then (assuming you took both junior year) go for it.