I have a Barbie with a solid body and the trademark R in a circle. How can that be?

She has the face of a #4 with a solid body. She does not smell like crayon. She came wearing a black and white striped suit. She is a nice even beige color without any fading. She has the flocked scalp under her ponytail. She does not have any greasy face. Everything about her says #4 except that Mattel says that the trademark on her which is the R in the circle is a number 5 or later. A number 5 had a hollow body! Yikes! Does anybody know how this can be? Also, her foot is not marked Japan and her box just says imported by Mattel.