Question about skill booster ( Major Spoiler Alert )

[Que]

When I first learnt there are probably 20 active skills and I can upgrade them twice ,
I was surprised because , that means there are at least 40 skill boosters in the game .

And now , I unlocked Mark Slayer and apparently I can upgrade his active skills , too .
This makes me worried a bit about the amount of skill boosters I can get in the game .

Are there enough skill boosters to fully upgrade both character's active skills ?

[aquatorrent]

Yes there is an achievement for it too
But the gumdrops are limited, you cant use them all to all of your skills

[Que]

That's a relief , thanks .