Flora of China includes R. laevigata f. semiplena. I think that’s what Don photographed. There’s another photo of a semi-double Laevigata bloom on HelpMeFind. I’ll add the form to HMF.
Link: www.efloras.org/florataxon.aspx?flora_id=2&taxon_id=200011269
Cass, that would account for the extra petals - but what about the color variation? The species is only described as being white. Without a formal description of an infraspecific taxon that allows for other colors, it’s virtually impossible to conclude that they are the same. FWIW, that picture on HMF with semi-double flowers doesn’t quite have the same leaves as other R. laevigata, and I would say the look of the flower buds adds to the suspicion.
I think the picture at HMF is in error as well.