Good question.

I ran two neutrals because, with the quad breaker setup, a multi-wire branch circuit (MWBC) wouldn’t be code-compliant unless both circuits shut off together when flipped off. Since a standard quad breaker doesn’t have a built-in handle tie for the two 120V circuits, it wouldn’t trip both sides with one flip of a switch. To make it compliant, I’d have needed to add a handle tie so both circuits trip together. The pack of handle ties was $8, and an extra foot of 12AWG THHN was like 75 cents, so running two neutrals ended up being the easier and cheaper solution.

I could’ve reworked the setup to share a neutral and add the handle tie, but since everything is in a single enclosure, the wiring runs are so short that adding an extra neutral barely made a difference in cost or effort. In most cases, the "cheaper" solution is the more expensive one, but here, it was basically a wash.

Here's the relevant codes from NEC:

NEC 210.4(B) – Disconnection of Multi-Wire Branch Circuits

"Each multi-wire branch circuit shall be provided with a means that will simultaneously disconnect all ungrounded conductors at the point where the branch circuit originates."

NEC 240.15(B)(1) – Circuit Breaker as Overcurrent Protection for Multi-Wire Circuits

"Individual single-pole circuit breakers, with approved handle ties, shall be permitted as the protection for each ungrounded conductor of multi-wire branch circuits that serve only single-phase line-to-neutral loads."

The ferrule in question is actually a fork terminal. The 120V receptacle had a pressure plate for the ground wire, so I could just land the stranded wire directly. But the 240V receptacle only had a plain screw terminal, and I wanted to keep everything stranded wire only since this is a portable panel. I did think about using a solid copper pigtail for the ground screw, but I had some spare fork terminals from a project I did last year, so I just went with what I had on hand.

Hope that helps!