How does new PDR work?

Did a bit of testing on Chief Oblivion Guardians (PDR 20) and White Fangs (PDR 5).
I have 123% Ignore def in my stats window, so should be hitting the same on both.
I didn't.
Using multiplicative Ignore Def, my actual is about 79%. The numbers I got were consistent with this.
Screenshots will be posted when it's not 2AM here, sorry.