Andrea. How strange, they are completely different blooms too. I'll be interested to hear what the experts say.

and they are definitely on one plant? I wondered if a self sown seedling is mixed in with the root stock and that has produced a different coloured bloom. How long have you had it?

I’ve had it for a few years and kept persevering with it as no flowers previously, it’s in a fairly shady place so this year I’ve cut back plants around it to give it more light and it seems to have worked. I think another seedling must have got mixed in with it and will take a closer look.

This is peculiar, but not unheard of. More common in hybrids. Unstable genes - occasionally one trait is expressed over another. Goes back to 5th grade biology and Mendel with his pea plant experiment. If you have a free moment, look up Gregor Mendal. A Fascinating read.