Helbrute Fist Question

I have a question regarding the points when adding second Helbrute fist. With Chapter Approved, GW updates the point for Helbrute fist to "Helbrute Fist (Single/Pair) - 40/50". I would like to know how this kind of wargear point works. Helbrute point starts with 72, if I add second helbrute fist, what gonna be the total point for helbrute now?:confused:

One powerfist would be 40 points, two would be 50 (because having two isn't much better than just having one.)

So:

72+50=122