It's a similar blade combination. A "Carpenter's knife" was a jack with two full length blades. The handles varied a bit... straight jacks, curved jacks, bullet end, etc. And the main blade can be either a clip or spear. The secondary blade is always a full length sheepfoot.
The Churchill is a "double-end jack". Typically, stockman and cattle knife type double-end jacks have a spey blade or sometimes a pen blade. But there are rare examples with a sheepfoot. Here's one with spear main blade and sheepfoot secondary using the parts of a Eureka (fancy cattle knife handle/die).
On the oldies, the spine of the sheepfoot was usually parallel to the handle. But it looks like it will be angled up when closed on GEC's knife (like on a knife with 3 blades). I might tinker with the kick if there's room. I'm looking forward to seeing the inside of the well.
Years ago, I had suggested something similar for the forum knife... and a couple years later we did get one made by CSC before they closed their doors. One of the nice things about the double-end jack is that a catch bit can allow the main blade to be full length. Whoever invented the catch bit is in my personal cutlery hall of fame!
Here's a comparison of two pen knives. The knife on the right has a catch bit and the main blade is longer than the knife on the left that lacks a catch bit.