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I thought I was growing "Mucho Nacho", however, they don't look like any pepper I've ever had.

I got that too when I planted what was supposed to be chiltepin seeds.
I think it is soloanum nigrum or solanum americanum. They are in the solanaceae family with a common name of black nightshade. In Hawaii they are called popolo because when they mature the berries are inky black. The difference between the two varieities are in the leaves. Both of them can be weedy because the birds will eat the berries and spread them. Popolo does have medicinal properties and can be used as a dye.

I have grown mucho nacho and the leaves don't look like that.

https://ipm.ucanr.edu/PMG/WEEDS/black_nightshade.html
https://data.bishopmuseum.org/ethnobotanydb/ethnobotany.php?b=d&ID=popolo

Maybe the hybrid process didn't take .?

Mucho Nacho is a jalapeno. It probably was a weed in the pepper field and was harvested accidentally. They are in the same family so the seeds would be similar.

Birds eat the black berries and drop seeds everywhere. I end up with them growing them under where they tend to roost….

Wow.... You'd think a seed company might keep that from happening

The seed company usually buys seeds from seed growers. They rarely grow all of the seeds themselves. They usually depend on the seed growers processing and labeling the seeds correctly. It all depends on how big the fields are and how the seeds are harvested.