Very late, and I understand it may have updated since, but I remember seeing this post and deciding to forgo having two cocks for a while because of it. Now, I happily have two (finally did it to ease Etheryn in with a smaller cock before my primary python) and find there's a lot of scenes that make use it, there just aren't enough scenes purely for two. I mostly see two when topping a guy roughly, mostly in victory sex (centaurs and corrupted lupines I know fs with the anal option; topping brint roughly also has both) where the two will go in one hole, or if it's more than a twosome then usually it'll get mention and used (like with the cat harem), but there are often mentions of the two even in scenes where one is getting most or all of the love, though they're easily missed if you're skimming.
I do, however, think it needs some refining. Like there are times where it will mention both dicks in the ass (for example) but then speak in terms of the knot as if there's only one, despite both of them being knotted. I think there should be more scenes that directly use both of them (like how there is for masturbation), rather than primarily just a couple altered or added-in lines to scenes more so meant for one. I think in general CoC2 should have some more variation, more choices branching off choices for different sex scenes, and the double cocks is a great example of one way we can have a whole lot more variety. But as it stands, I definitely don't feel that having double cocks is entirely useless, just not as well utilized as it probably should be.