Interesting experiment (please allow me to call what you did that way).
Unfortunately, the two pseudo stems started showing signs of distress. Either the competition for resources is taking its toll on them or this is due to a pathogenic disease, I would not know. However, I suspect the former.
I agree with your conclusions about the demand on resources that may be too important relative to what your soil can produce. Isn't it easy to fix with supplements to be added to the soil?
If anyone is interested in the double bunch plantain sucker, I am open to sending it across for free. However, the shipping cost will be on you.
Thanks for this offer of sending seeds away. I am however not interested. I don't think banana trees will live well in the region where I stay.