Do bard levels from Cleric (Evangelist) and Bard stack for the purposes of Inspire Courage, Inspire Greatness, and Inspire Heroics? Do bard levels and other bardic performance-granting class levels stack for the purposes of effective bardic performance level?
no, it's like channel energy. A paladin channels energy like a cleric, yet their levels are separate, 2 different pools. And unless it says it stacks with like abilities, it's granting you a second pool of it.