This is where I would disapprove of the system. It sets up a farming situation geared for 3 profs. Advy, agent, and shade - all stealth/cloak and wait to AS/SA/Dimach and steal your kills and increase their counters.
Duels could still work with 24 hour timer that any player /dueled can only count 1x toward kill counter every 24hour period to prevent farming. As far as over rides for pvp checks, any player city can have that building that does the same thing.