What little I know about the hobby tells me that the red one got the natural sunlight and developed faster than the green one. Beautiful flowers. I hope my leaf cuttings grow up to look like that!
Here's a rider to your query: I have two adult P. primuliflora. One starts flowering white and ends up iris colored. The other starts out iris and ends up iris. They are both primuifloras, to my knowledge. both have produced plantlets. Why is the difference in flower color development?