SELECT Name, SUM([Users Number]) FROM
(
    SELECT e.Id, CONCAT(e.FirstName, ' ', e.LastName) AS Name,
           COUNT(r.UserId) AS [Users Number]
      FROM Employees AS e
      LEFT JOIN Reports AS r ON e.Id = r.EmployeeId
    GROUP BY e.Id, e.FirstName, e.LastName, r.UserId
) AS t
GROUP BY Id, Name
ORDER BY SUM([Users Number]) DESC, Name