Hi,
We've had a look at this. This was introduced in version 3.17.0.2 to improve the rendering of NUnit tests that have a TestCase attribute that contains escape characters or unicode. NUnit adds slashes to the testname that it reports back. We've tried improving on that rendering, but since it causes these side effects the change is rolled back. This rollback will be in the next release.
Again, thanks for sharing this with us!