select sub1.hacker_id, sub1.name 
from (
select h.hacker_id, h.name, count(s.hacker_id) as count
from submissions s
inner join challenges c on s.challenge_id = c.challenge_id
inner join difficulty d on c.difficulty_level = d.difficulty_level 
inner join hackers h on s.hacker_id = h.hacker_id
where s.score = d.score 
group by h.hacker_id, h.name
    ) sub1
where sub1.count > 1
order by sub1.count desc, sub1.hacker_id asc