Prismatic Spray stuff

[Dmdork]

I cast Prismatic Spray

I roll an 8. I roll twice more, rolling two 6s (possible petrification). Does target make two dex saves? What if target fails them both? Is target now making two con saves at the end It's turn, collecting three of a kind, twice? Lol

What if I roll two 7s (possible banishment)? Does target make two dex saves? And if target fails them, is target now making two wisdom saves at the start of its turn?

[UnintensifiedFa]

I would say no.
Prismatic spray is a spell and as such would be subject to the rule against multiple identical spell effects occurring at the same time.

However, if they succeed on the first dex save, I would force the target to roll the other save, as the magical effect is not in place.