3 sets of fan leaves per node on newly topped plants.

Nothing to be concerned about , once in full flowering the stems are growing in an asymmetrical way even if you have 3 stems per nodes. I had experienced that variations on some of my plants and most of the time the only problem is that they are more leafy than regular plants so the buds are a bit harder to trim. I don’t know the name of that mutation (edit : it is whorled phylotaxy ) Edit : It's important to note that whorled phylotaxy (plants growing three or four leaves/branches per internode) is not the same as polyploidy. The two terms are often confused. One reason for the confusion of the two ideas is that both refer to a 'doubling' of cannabis plants - genes in one case, foliage in the other. Polyploidism can only be confirmed through genetic mapping