[SR71]

It's possible for non graded thermal layers in the atmosphere to act as wave guides for RF and visible light. Seems unlikely, but possible that light is being introduced at a different incidence to the droplets?

I think but has it though, it's just simultaneous reflection rainbow and double rainbow.

Just this summer, I saw my first ever double rainbow. I wonder if this type of thing will become increasingly common as the atmosphere warms. I think air can hold 6% more vapor per additional degree celsius or something like that. Seems like that would increase the likelihood of refraction.