Yes I did set up a second wallet according to biblepay-central.org instructions.
It says that you can POW mine with multiple wallets. Just copy wallet.dat and add utxooverride=-1 to the config.
So if I understand correctly that is not the case?
Oh well... better disable the second wallet and hope things return to normal.
Yes, this is definitely possible (I'm currently using that method myself). However you have to remember that your second wallet (the one that you copy to all your POW miners) also has to be connected to a (different) CPID which has to solve some BOINC jobs. Otherwise that won't work.