Not unless FD has changed the rules since I did it. As long as you're pledged to one power, killing (NPC at least) ships that are assigned to an enemy power will only get you power play bounties from that enemy power (and merits from your own). With the rise in power play bounties on your head, you will of course become more attractive for powerplay NPC bounty hunters (which means you won't have to go out looking for them, they'll come looking for you

). No notoriety involved.
You may have encountered powerplay ships in regular gameplay - ships with names like Torvalds Shield or Federal Enforcer or something like that, who complain, after scanning you, that you're not worth it wasting their time. If you have a corresponding powerplay bounty on your ship, they won't stop at complainig...
I'd suggest to visit an IF when you leave your power's service to clean those bounties - I have no idea what happens otherwise.