I read an article of an interview where Butch said that he believed they may have crossed with a Cumari Ou Pasarhino. (Not sure about the spelling.)
What's funny is that people swear by certain seed sellers, but what they DON'T do is pay attention to pics and videos made by those very same people where they show their plants are touching. Yet people STILL buy from them. I wonder why...maybe it'ss because, even though crosses DO happen, as long as you take the correct precautions, crosses are not that big of a deal.
Keep this in mind...even IF your plants are touching, all that means is that IF your flowers are getting cross polentated, the bees and such are only going to the most outer flowers. So, if you're going to save seeds, save them from pods on the inside of the plant.
Sure, you can stress yourself out by doing crap like putting different types of baggies, etc., over flowers; supergluing stuff, whatever. Why go through all of that stress when it's not needed? Even of someone did all of that b.s., it doesn't always work anyways.
Here is MY suggestion....save seeds from pods pulled from the middle/inside of the plant. When you save seeds, put seeds from different peppers in different baggies. That way if one doesn't grow true, throw that baggie away. That's IF you want to go through all of the trouble. I personally enjoy crosses.