Technical Issue

I have a very urgent question here, it would be highly appreciated if you can provide answer to me as soon as you can . My son did his test once in Khan Academy but the system shows to his teacher that he did multiple times . He explained to his teacher that he only did once but it's difficult to explain why system shows multiple times.  If we can not figure out reason , it will make the kid lose his credibility, now my son feels very frustrated.   Do you know what caused this problem and whether you met this kind of situation before ? I look forward to hearing back from you.