Below are two screenshots taken months apart. One while using UT on focal and one that I took yesterday. Look at the network indicators. One shows two while the other one shows one.

@Vlad-Nirky If I remember correctly, UT supported two sim cards on lancelot, just that you couldn't use the second sim card for mobile data like it says on the devices page. But you could make and receive calls using both sim cards.
Also, merlin is not lancelot.

Hi guys.. New here. I flashed Ubports on my lancelot (24.04-1.0 Stable) a few hours ago and I noticed that sim 2 wasn't being detected. Last time I flashed ubports (focal) a few months ago both sims were being detected.
So I went digging around and saw that the running kernel is 4.14.355-openela-merlin, which I don't think is the correct one- I correctly selected lancelot while installing. I used the ubports installer in windows 10.
Under imei only one imei is listed, the other one just has 'none'