I have both but don't remember where I ordered Rose Heart from so can't attest to how reputable the seller is. I got Bess Bockstoce just a couple of years ago, definitely 2 different blooms. Here's a pic of the bloom with faded edges but it's from several years ago.
The pics I took last year were from too early in the bloom life to see the fading. It was horribly bent from our Mother's Day weekend blizzard so I put a peony ring on it really late to get it off the ground, not the best peony display ever....
This is my Bess Bockstoce from last year. It was taken the same day it opened fully so you can tell how much lighter it is than Rose Heart. Got it from Swenson's.
Rose Heart is ready to pop this year.
