title: Multiple Elasticsearch Inner_hits queries are not giving results as expected
body: <p>I am trying to retrieve child document content using inner hits feature of Elastic search. My query contains two has_child clauses as shown in the code snippet below. What I have observed is that I get only those child contents in the inner hit response that are part of second child clauses. It looks like the last inner hits overwrite first inner hits. </p>
  
  <p>Is there any way to get both inner hits?</p>
  
  <p>Here is the query I used.</p>
  
  <pre><code>{  
     "query":{  
        "bool":{  
           "must":[
  
              {  
                 "has_child":{  
                    "type":"subformcontent",
                    "query":{
                      "bool": {
                          "must": [
                              {
                                  "term":{  
                                      "txt_1.raw":"Malayalam"
                                  }
                              },
                              {
                                  "term":{  
                                      "parent_field_id":"1000"
                                  }
                              }
                          ]
                      }                                            
                    },
                 "inner_hits":{  
                       "size":10
                    }                  
                 }
              }, 
              {  
                 "has_child":{  
                    "type":"subformcontent",
                    "query":{
                      "bool": {
                          "must": [
                              {
                                  "term":{  
                                      "txt_1.raw":"Malayalam"
                                  }
                              },
                              {
                                  "term":{  
                                      "parent_field_id":"1001"
                                  }
                              }
                          ]
                      }                                            
                    },
                 "inner_hits":{  
                       "size":10
                    }
                 }
              }
           ]
        }
     }
  
  }
  </code></pre>