when I have Karlov of the Ghost Council and Soul Warden on the battlefield - and I cast something like Lingering Souls - does Karlov get twice the +2/+2 counter since two spirits enter the battlefield, or only once since I cast Lingering Souls once?

Same thin applies to beautiful cards such as Conqueror's Plegde - does Karlov get 6 times +2/+2 or only once?

Thank you for your help!!