Have you ever seen a blue willow plate that has 4 birds?

Yes I have seen a blue willow plate that has 4 birds. My mother has one. It was a misprint and is worth a lot of money. I would take it to several antique dealers if you are wanting to get an appraisal on it. I suggest several, because there will be some that will tell you it is not worth anything more than the original design with two birds. I hope this helps.