I have never seen this before. I bought a small root (2-3 eye) on sale from BloomingBulb for $3 in fall 2015, it was October so I planted it in a pot and it overwintered fine (it never went outdoors). The name was very generic - Double Pink. It had broad leaves, different from other lactiflora peonies (to my experience).
Last summer I planted it and this spring it started to grow with the same kind of leaves. After some time it grew "ordinary" lactiflora leaves:
Why are there 2 kinds of leaves on the same peony? Is it a young peony? I am very curious.
I have this happened with two of my peonies. One that I planted on the same spot of Paula Fay that I dug up last year. Apparently, I did not get all the Paula Fay roots so that it is sending up a stem right in the middle of my new peony planted in that same spot. Another is with a root that I bought from Bannister Garden. It is supposed to be Mrs. FDR but it is sending up two different types of foliage. Really strange. I don't know what to make of it.
Thank you all for your opinions! I will see how this peony grows, it indeed looks strange, maybe it's young, maybe something else I hope to remember to come back to this thread next spring and tell how it grows