I grew a batch of violas from seed that had set from some shop bought plants. One of the plants that has recently come into flower is unusual in that it carries two distinctly coloured "faces." I've not seen this before and contacted a well-known seed company to ask them if it might be an unusual strain in which they might be interested but, as they haven't got back to me, I assume this is something already known. Originally the bottom half of one flower-head was light blue while another had a pale yellow lower half but now it has produced in addition to the blue head two heads with creamy-white lower halves. Have other growers met this before and, if so, just how common is it?