There are quite a few semi-double pinks, you might want to put as much info in a follow-up message as you can provide. What zone are you growing in? Was this actually blooming in mid-July when you posted it? If so it's probably a very late bloomer. Did your other discovered peonies bloom? Before or after this one? How tall/wide is the plant? Is there a single bloom/stem or does it have side blooms? Is the color in the pic pretty accurate? Is it fragrant, if so how much? I don't recognize this one , is there anything completely unique about it that we don't see in the pic? I found a search utility that I've used to try to ID some of my peonies, you might want to try this site to find some likely suspects. Good luck!

Here is a link that might be useful: Heartland Peony Society Peony Name Search Database