So, when I change the launch to another invocation, the results slightly change. Is there any way to get an average result?
There is no averaging of results within the UI. You can export the results from e.g. the Raw page as CSV and perform any further analysis using third-party tools like Excel. You can likewise export as CSV from the command line, either directly during profiling or when importing an existing report. On the command line, you can furthermore use the --summary option to see min/avg/max values for various groupings, but be aware that not for all metrics averaging makes sense in all cases.