Can someone explain how this one hibiscus plant can produce two different coloured flowers?

My dad has this peach hibiscus which grew from a cutting I gave him a few years ago. A red bloom has appeared these past few months. You can see both the peach and red bloom coming from the same trunk.
When I grew the same hibiscus in my garden it was always peach but there was a time where one flower had a red petal and the rest were peach. But it just happened once.