  In this work we study a simple evolutionary model of bipartite networks which
its evolution is based on the duplication of nodes. Using analytical results
along with numerical simulation of the model, we show that the above
evolutionary model results in weighted scale free networks. Indeed we find that
in the one mode picture we have weighted networks with scale free distributions
for interesting quantities like the weights, the degrees and the weighted
degrees of the nodes and the weights of the edges.
