Breeding (need help)

So i hope anybody knows:
i’m trying to breed the scarbearer, this can be done with skullcrusher & and son of skullcrusher (kinda messed up father + son) but whatever.
i can also use 2x son of skullcrusher, which is slightly faster but i don’t know if the changes get lower as well.

does 4 star + 5 star have a bigger chance of a 5 star outcome?
or should i just breed 2x 4 star for it.

Thanks in advance!