Makes sense Joe. I'm use to seeing the Moore sheath with the inside of the butterfly being separate all the way back down to the bottom of the stitch like this one.
But here is one of Mitchell's Moore sheaths that looks more like a Heiser stitch
Here is a Heiser butterfly.
Here is another Moore model 7 sheath that has the separate butterfly where both stitch lines join at the bottom.
Your scenario makes perfect sense Joe. A Moore sheath finished by Heiser.