I play a Hexblade Pact of the Blade warlock and thought, "Hey, if I throw a natural 20, are my bonuses from Improved Pact Weapon and Hexblade's Curse duplicated?"
(The same applies to bonus damage from my fallen aasimar's necrotic shroud and other bonuses that consist in flat bonus damage rather than in extra dice as the d4 from bless.)
As I have searched and couldn't find an answer, I thought about asking by myself.
PS: I know ability modifiers aren't duplicated and extra dice from, divine smite, etc are.