Twins to different fathers

It occurred to me today that I have read hundreds of RH stories and quite a few of them have involved the FMC giving birth to twins, but not one of them have ever been twins where they are biological to two different fathers, which really surprises me, since although it is rare, it’s 100% scientifically possible. I always get to the end of a book half expecting this to happen when the storyline goes to twins, but I’ve never seen an author use it once. Does anyone out there have any recs where this actually does happen?