I've kept four of the best seedlings from Rosa bracteata X (rugosa x palustris) and numbered them BH1 thru BH4. This is the first time I've seen any of these have ANY repeat bloom. This is BH3 (one of the two whites). BH1 is the one I've called the "pink monster" in the past (with the heavy influence of rugosa showing in it's foliage). This BH3 has more of the palustris look showing in its foliage. The leaf in the upper left of the picture is a weedy blackberry growing through. The foliage underneath is the rose.
I thought that I'd seen a bloom on it from afar about a week ago (but just figured it was a fluke), and when I went down to check this one yesterday, I see that there have been five recent blooms scattered all over the bush. So, I guess it's not a sported/mutated branch but maybe rather just a general tendency to have a few late blooms. It also seems to be one of the cleanest as far as leaf spotting goes. I hope it continues to show these characteristics in the future.