This product is an Anderson  three way (parallel) electrical junction. Also referred to as a Tri, or Y junction or connector, or even a three way splitter. These are useful anywhere in a system that you want to add another connector in.

These products are common in the marketplace, but this way of building them is unusual, as the power has two ways to flow to each connector, reducing resistance and adding physical strength. When I built the first one, I was reminded of the schematic drawing of a type of alternator design, referred to as WYE.

These could be added into an Adapt-A-Camp system at the battery end if you wanted to feed in your (regulated) solar panels at that point, at the Adapt-A-Camp if you needed another outlet there, or anywhere else you need to turn one Anderson connector into two.