So that you can easily rebuild and re-run each one with difference in build settings, instrumentation, etc, and get comparisons between the baseline and the mod

So that you can easily rebuild and re-run each one with difference in build settings, instrumentation, etc, and get comparisons between the baseline and the modified version, without having to check out a different branch each time. Sometimes it's just quicker to work with two separate working directories than switching branches in one.