post choas- db's question

example:

my dagger potential line is : boss 30%, ignore df 15%, attack 6%
my katara potential line is : boss 30%, ignore df 15%, attack 6%

My question is 1. does dagger and katara boss dmg stack and become boss 60%?
2. does dagger and katara ignore df stack and become ignore df 30%?

I appreciate to those player who has test on this and reply here.