1. This is a known issue right now - Only last names are displaying
2. Moderators, admins and Ambassadors have the ability to mark answers as correct. Do you have a link to the thread for reference?
EDIT: I'm guessing this thread? Hierarchies with Measures?
I will say this - as someone with the power to mark the answer as correct, it is very easy to accidentally click that button.
Do you have the option to unmark it as correct? If so, I would go ahead and do that.