Their are no "dual state" agencies.
An agency is either created by a single legislature or its not. Two separate state agencies can work together but they gain their authority via both individual legislatures.
Not surprised the AGs don't note the agencies. Why would they?
? needing to be answered to see if an agency is subject to record request:
1) who formed the agency
2) how was it formed
3) where does it get its $$$$
4) who supv. the agency
5) does anyone tell the agency what to do
Even private companies can be subject to open meetings laws....depending on the gov't-company relationship