Yes, it can happen. A good example of this happening naturally would be the Waterwheel Plant (Aldrovanda vesiculosa), which happens to be an aquatic and carnivorous at the same time. This plant would make a Pondie-Sundee Plottie.
Another example would be pines and spruces, which are naturally Saigi-Anblums or any fruit trees, which would be a Saigi-Angie.
This type of sub-species can also happen artificially by breeding two Plotties of different sub-species, creating an SS-Chimera. However, these are artificially engineered through the use of Fertilitiy Elixirs or Lab Kits.