Curtis made me curious so I researched. If you are too, you don't need to:

I read a couple of papers but the best resource I found was a blog called "Life is short but snakes are long". The name is funny and I love it but I found it the best because it has pictures and explain things in a easy to understand way.
So, about Curtis' 2 sex sticks. Male snakes (and lizards) have 2 and one scrotum for each; however, they only use ONE at a time. This is a way for them to have time to restore the sperm count (it can take 3 days) when they have opportunity to mate more than once in a mating season. Usually they have one on each side (right and left) and in case you didn't know, snake's penises are retractable. When not in use they stay in a pocket inside their tails which is why a male's tail is usually thicker and longer than the female's.
A fun fact: snake ejaculation can take several HOURS.
Fan fact 2: snakes can mate even outside of mating season.
Fan fact 3: female snakes can store sperm of multiple partners and choose which ones she wants to be impregnated from and WHEN. The stored sperm can be used YEARS after it was "harvested". Some believe they may even be able to choose how many from which, since they are able to birth from different fathers at once.
For the sake of our FM here, I hope Curtis penis is similar to a human one because most snake species have spikes on their penises so they can lock on the female (this is also know in feline species like lions too). The females of same species apparently are not hurt by it but the ones who aren't are (lucky of them, the lionesses actually feel pain with the removal of the lion's penis which is used to stimulate their ovulation). So... in a world where you can mate with other clans just fine, I suppose the spikes are not only not needed but would be a hindrance. I'm assuming he doesn't have spikes. I mean, she didn't seem traumatized.
Another curiosity: some snake species actually give birth instead of laying eggs! Apparently Curtis is not from one of those species since the type of gestation, birth and species of the babies seem to be determined by the father in this world... I also hope Curtis is monitoring the temperature and humidity really well because in real snake eggs, moving the eggs after they are laid may cause egg death because of those changes. Also, like in other reptiles as well, the gender of the babies inside the eggs is determined by the temperature! So eggs on the bottom or top of the pile usually hatch with a different gender, not always. It's more common when the eggs are buried. The hotter temperature make them females and the colder makes them male.
Curtis is likely not a Python since those snakes are capable of incising the temperature of their clutch by 7-10°F. In my limited knowledge, I think they are likely the hottest snakes in body temperature. As far as I understood poisonous snakes tend to be more caring of their offspring than other snakes so I'm optimistic of Curtis being a good father.
I'm likely going to research the other potential fathers of our MF's kids as the story progresses in case you guys also wanna know.