This is a rarity. The first time I see that they come out new par of apendix under the cotyledons, they look new leaves, but under the cotyledons ?. Someone can explain it?
Had 2 cases like yours! One in one pot of my previous grow (i take out those "apendix") and the plant developed beautifully, and same is happening in another pot of my cookies grow! All auto-strains!
I had the same thing happen on my Orange Diesel which is currently flowering. I think it is just a random genetic issue and has no impact on the final health or other characteristics of the plant. In my case I let it keep growing and it produced some odd leaves at first (lots of thick stacking of growth almost like a succulent) and then eventually formed a small branch with some airy buds. It's always fun when you have little unique things like that happen to your plants 👍