OK, a few questions here-
a pa who goes back to school to be an aa can do and get paid for doing operative anesthesia. aa training is equivalent in every way to crna training and they compete or the same jobs. currently aa's can only work in 15 states. this is increasing yearly.
there are dual pa/aa folks out there who have done both programs. there is currently a bridge program from pa to aa but it only takes off 1 semerster and is fairly new. the dual folks out there now have done both programs in total.
a pa/aa could work in the o.r. doing anesthesia and in any setting that a pa could work so they might find themselves working in more than 1 job( er 2 days/week, o.r. 2 days/week) or for an anesthesia/critical care group where they could cover the icu and the o.r.( in this setting they would probably make more than someone with just 1 cert).
doing both involves around 4 yrs of school after college so you might as well become an md/do at that point in my mind unless you worked as a pa or aa for a few yrs and decided you really wanted to do the duties of the other.
if at the beginning of your career and considering both I would do medschool instead. hope thatanswers your questions.
-e