so headwingless ones are rare?

Hah, re-checking my sources there's actually a mistake there! Great, we'll have to redraw that panel.
Turns out they are so rare they don't exist - they actually just get the headwings and never the backwings. Oops.

"As for Cubi, which is probably the main reason for asking. The vast vast vaaaaaaaaaaaaaaaaaaast majority of the time when a child is born that will one day become a Cubi, they are born with wings. In some ways this is the best sign for a Cubi parent that their kidling will become a Cubi when they get an adult. Though it has happened very rarely that they do in fact just end up being a being with wings. EVEN MORE RARE, and I'm only mentioning this now because god knows someone will ask despite this probably opening up a can of worms, a child born without wings can become a Cubi. But this is really really REALLY uncommon and only happens in clans that have no clan leader. (How rare? Well at the time in DMFA current, there aren't any about and there probably wont be any during the run of the comic) The end result is usually a Cubi that only has the headwings, no backwings at all. Which tends to put them at a really big disadvantage to other Cubi since the backwings have a big use of being extra mass that allows for a lot of their shapechanging abilities to work well."

https://clockworkmansion.com/forum/index.php/topic,8929.msg361895.html#msg361895

Quite the detail to have to redraw.

Merlin is very fast. It was just a matter of rubbing out the backwings and torn shirt, and adding headwings instead.
I think I will upload the original version to scraps for posterity.