It is not normal, but does happen from time to time.
They are known as "whorled phyllotaxy"
Sometimes the main stem will be "tri noded", other times just a branch or two will be "tri noded", which is a genetic mutation, not necessarily caused by polyploidism. From what I think I know, either the whole plant is polyploid or it isn't. To have just one or two branches being polyploid while growing from a normal diploid plant is highly improbable and most certainly not possible, as every cell of the plant shares the exact same chromosomes.
A plant that is entirely "tri noded", main stem and branches, is triploid, and usually inferior to either diploid or tetraploid plants.
I always thought wholly tri noded plants (main stem and branches) also had a bigger inclination to be male and have always culled them, but according to one contributor, they can turn into and stay female through to harvest.
The plants that I have grown that have had the occasional "tri noded" branch/branches, have all flowered normally - not sure if they had more bud, as the normal "two noded" branches had bigger individual buds than the multiple "tri noded" buds, which were smaller than the normal "two noded" buds.
Eleven bladed leaves are very common, but 13 bladed leaves are quite rare. I have only seen good examples about, maybe, 12-15 times over the last 35+ years and on all types of cannabis; Sativas, hybrids and Indica plants. I have also grown plants with three nodes around the stem, but have then had two "noded" branches and not "tri noded" ones. However, as I stated earlier, due to my fear of triploid plants being male, have always culled them. Might have to keep the next one and see what happens, providing I have the space to run an experiment.
Good luck with your grow, it will be most interesting to see what happens with this plant.
Hope this helps,..... Organoman.