So which button is the primary call to action? You are presenting users with 2 actions to take, colour doesn’t make much of a difference here because the text within the buttons play a bigger role.
You should be focusing on getting the user to take a primary action and not have to think about which button is the best option, this will lead to cognitive load and most likely frustration (what happened to me just now)
Do they both even need to be buttons? Maybe one is a button and one is a text link, for example. In that case you can keep the button green and not worry about colour theory at all.
Or, have the primary button green, or whatever colour, and the second button outlined or ‘ghost’.
Read about call to actions and information scent here:
Hope that helps.