This paper aims to model asymmetric operation in double gate junctionless FETs. Following a rigorous approach, we find that asymmetric operation can be simulated by combining two symmetric junctionless FETs, what we call the virtual symmetric device concept. In addition to the benefits in terms of compactness and coherence, such equivalence is used to develop a complete charge based model for independent double gate junctionless architectures, including mismatch in gate capacitances and material work functions.