title: Laravel DB raw returns double sum
body: <p>There are two tables: <code>users</code> and <code>score</code>. Score table has columns <code>game_id</code> and <code>points</code>.</p>
  
  <p>This query </p>
  
  <pre><code>    return DB::table('users')
          -&gt;where('users.id', 36)
          -&gt;leftJoin('score AS education_score', function($query){
              $query-&gt;on('education_score.user_id', '=', 'users.id')
                  -&gt;where('education_score.game_id', 2);
          })
          -&gt;leftJoin('score AS experience_score', function($query){
              $query-&gt;on('experience_score.user_id', '=', 'users.id')
                  -&gt;where('experience_score.game_id', 3);
          })
          -&gt;groupBy(['users.id', 'users.name'])
          -&gt;select([
              'users.name',
              DB::raw('SUM(education_score.points) AS education_score'),
              DB::raw('SUM(experience_score.points) AS experience_score'),
          ])
          -&gt;get();
  </code></pre>
  
  <p>should return </p>
  
  <pre><code>[
      {
          name: "JANE DOE",
          education_score: 70,
          experience_score: 2
      }
  ]
  </code></pre>
  
  <p>instead it is returning exact double</p>
  
  <pre><code>[
      {
          name: "JANE DOE",
          education_score: 140,
          experience_score: 4
      }
  ]
  </code></pre>