within emacs, can I have 2 cider buffers running at the same time, for use in different namespaces?

You could, but you're probably going to have a bad time.

I do this sometimes when playing with core.async. mostly it works.

hrm, welp thanks for the warning

Does anyone get 'Symbol's value as variable is void: hi'

when trying to use cider-eval-last-sexp?