Private Last Mile tests, like Last Mile tests, can be run in a batch group that runs the tests through the same machine during a given test run to allow for added comparisons.
Between one test run and the next, things can occur that stop the machine from returning results. For instance, the Peer could shut down or lost connectivity. It is also possible that data could be marked as suspect and be hidden from the results. Data might be suspect if a critical agent error occurs or there is an issue with the bandwidth test.
If any of these events occur, you would see slightly different test counts in the results.