For reference, this is the source of the text...

DESCRIPTION_POINTS_FOR_COMPLETING=The number of points a member gains for completing the quiz. In the case of a test, these will only be allocated if the test is passed. Please note that for a competition these points will be given to anyone entering – “prizes” must be given manually. In order to stop members getting the same points many times, you may wish to set a very high “Reattemption time”; alternatively if you want a low reattemption time but only allow a test to be passed, you may want to put successful members in a different usergroup that does not have permission to access the test (you can use match-key permissions to set that).

I've resolved this issue in v11. It's not a bug, it's just the language is confusing and process labourious. It's suggesting you MANUALLY move people to a usergroup upon passing a test, before they try again. Over complex and impractical.

In v11 it will now automatically know not to assign points more than once. And, hence I was able to carve out a lot of the DESCRIPTION_POINTS_FOR_COMPLETING language string.