We study the qualitative change on the principal configurations around non simple umbilical points which are codimension one bifurcation points in the space N1 of 1-jets of vector fields ν normal to a generic surface immersed in R4 with an isolated ν-umbilical point. We prove that, except for one point and under some generic conditions, the principal configurations around this class of non simple umbilical points are of the same topological type D23 which represent a bifurcation between the Darbouxian types D2 and D3 in the space N1.
