How to randomize the variables used by multiple virtual users in Azure Load Testing

I am wondering how exactly the virtual users function in azure load testing. I am uploading a few CSV files and using those columns as variables in my PUT JSON requests. Now if I had 50 users running, does that mean they all start at the top of the csv and work through all the lines in order at the same time or is it random? One of the errors I keep getting is due to the same request being sent at the same time so I am trying to randomize it to help eliminate the same data being sent at the same time.