Restart Run> includes all test cases that already passes making the re-run test case count bigger.
Re-running a failed test set using the Restart Run button (In Run History, click the "Restart Run" button), includes the previously passed test case count in the re-run.
For example, you ran a test set with 3 test cases. On the first run you passed 2 and failed 1 test case. Then you click in on the "Restart Run" button and pass the failed test case. When you look at the run history, it will show you 3 passed test cases. This makes it seem like you re-ran 3 test cases instead of 1.