I’m super curious if this trait will continue to manifest as the rose matures. There is another bud forming but it is slow to develop. One fun thing is the presence of anthers in the last photo. That gives hope that perhaps this unique trait could be passed on.
OFTEN! Some do it all the time. Others, virtually never. Tequilla Sunrise proliferated in my Newhall garden so badly I eventually culled it. Sometimes proliferation can be rather “interesting”. I raised this and hoped it would have proved healthier than it eventually did. 'Queen of the Desert' Rose Photo
It’s a terrible photo because it was getting dark on an already dim, wet day and I was short on time, but last year a version of this happened to at least one blossom on ‘Ames Climber’. I believe the second set of flowers (a little bouquet) did manage to open, but I don’t remember there being any more.