The loop evaluator write method is call once per output write. However, a processor block may have several outputs which means that the evaluator write method will be called as many times as an output is written. So in the case of a sequential processor algorithm with 2 outputs and 3 input data, the evaluator write method will be call 6 times.

After talking with @andre.anjos, the current solution proposed is to add the output name written to as a parameter of the evaluator write method so that the developer can chose on which one he wants to "synchronize" the evaluator output.