Are you talking about two plants coming from one one seed?
Had that happen only twice so far, from a TGA strain called kaboom.
One double seed had two females that grew pretty similar, slightly different heights.
The other double had a larger female and smaller male plant.
Only started five kaboom seeds so there was no question the doubles were from a single seed
Click on the image to see it full sized and check out those Siamese twinned seeds.