Yep. Had a couple of de Arbols that did that. Mine was worse. I had one ripe and one green twin. Looks like both of yours ripened together.

Scorpion Twins

First time I've seen it! I have a seedling now that I originally thought had 3 cotyledons, but on closer inspection there are two. It appears as if there were going to be 3, but 2 of them fused to make some sort of mutant leaf.

It happens now and then.

Here's a Billy Goat twin

They resemble Siamese twins in humans.
It is just a deviation from the norm. It happens all the time.