There’s no way to duplicate cards at the moment, however improved templates seem to be what you’re after. I’ve increased the priority of this, and then you will be able to create a template for the first card – after which you can use that to fill out titles, content, colors, tags, parents etc. At the moment the best thing you can try is using Raycast or similar to quickly insert repetitive information, like @JamesT mentions here.
Also @chipbrock, the quote you’re referencing from the API is from 3 years ago 
The API is very much a matured spec, and with Supernotes 3 this will be solidified further. So @isaiur is right, it would be quick simple to create a quick command or apple shortcut (if you use that ecosystem) to create 12 cards with the same name. We’re also in the midst of creating much improved documentation with examples.