Identical particles are indistinguishable but..
  It is shown that quantum systems of identical particles can be treated as if they were different when they are in well differentiated states. This simplifying assumption allows the consideration of quantum systems isolated from the rest of the universe and justifies many intuitive statements about identical systems. However, it is shown that this simplification may lead to wrong results in the calculation of the entropy.   Keywords: quantum mechanics, identical systems, entropy 
Alberto C. de la Torre and Hector O. Martin