has anyone ever killed an Ai's king and end up them not getting destroyed? only you find out about 15 turns later that they have rebuilt about 4 cities because of wandering settlers? this has happened to me many many many times.

ex: kill Johan of Arc. 7 turns later, find more french cities.

my theory is that when the king is killed, only their cities are blown up, not settlers.

You probably have respawn on.

nope. not on. I destroy the French's king and then the "you have destroyed the French" popup didn't come. then I wandered around, and I found more French.

Do you have mass regicide on? Then the AIs will have 7 kings/queens instead of just 1.

nope. Just regular Regicide.

I had Mass Regicide and I killed all Portugal kings.. and then from last city came to me 6 new kings and 7th stayed in the city :) I killed them all and I found 3 more cities with 7 more kings :)

Do you have mass regicide on? Then the AIs will have 7 kings/queens instead of just 1.

I've experienced exactly the same in PTW (unpatched i think). The AI king is dead and they immediatley get a new city and king. Only after the second time will they be finished.