As a Physics TA, while grading lab notebooks, I noticed that two students who had collected data together had very similar analysis diagrams and paragraph responses to questions, though their answers were not exactly the same. I noted their anonymous aliases and spoke with the teacher I work for about this, but I also let her know that perhaps the lab handout should specify which parts of the lab could be collaborative and which ones should be each person's own work. I decided to believe that their efforts to collaborate were a testament to their common desire to learn physics, and this is what drew them to work together on the write-up portion of their lab experiment.