Hi bro,
Can you take a closer look at the bigger yuma. Is the most outer ring of the adult yuma a bit purplish or pinkish? If there is, chances are the baby yuma you saw is actually a baby green yuma. Its pink because you can only see its most outer ring.
Another thing is that different yumas dun exist on the same rock. The only time you probably get different yumas on the same rock is when the LFS brought in different yuma and put them in the same tank. One of them dislodge from the rock and stick on the other rock.
Don't mean to disappoint you. Just sharing what i've experienced. Hope all turns out fine for you.