It's okay. You didn't vote twice. The first time you voted it went through the gtop100. The second time, MapleRoyals basically credited your vote and when it redirected you to vote, gtop100 probably told you that you've voted in the past 24 hours. You voted once and recieved rewards for one vote point. No worries about a ban!
Yup, as you figured out " it keeps saying "Your account is already logged in or your account name is incorrect. Please try again." means you need to be logged out for the NX to go through. And Ponder's right - you're fine!
