diff --git a/solr/CHANGES.txt b/solr/CHANGES.txt
index 398ad730393..f690ef6b51a 100644
--- a/solr/CHANGES.txt
+++ b/solr/CHANGES.txt
@@ -302,6 +302,9 @@ Bug Fixes
 * SOLR-5704: coreRootDirectory was not respected when creating new cores
   via CoreAdminHandler (Jesse Sipprell, Alan Woodward)
 
+* SOLR-5709: Highlighting grouped duplicate docs from different shards with
+  group.limit > 1 throws ArrayIndexOutOfBoundsException. (Steve Rowe)
+
 Optimizations
 ----------------------
 
diff --git a/solr/core/src/java/org/apache/solr/search/grouping/distributed/responseprocessor/TopGroupsShardResponseProcessor.java b/solr/core/src/java/org/apache/solr/search/grouping/distributed/responseprocessor/TopGroupsShardResponseProcessor.java
index c1138058e04..f7a22f09841 100644
--- a/solr/core/src/java/org/apache/solr/search/grouping/distributed/responseprocessor/TopGroupsShardResponseProcessor.java
+++ b/solr/core/src/java/org/apache/solr/search/grouping/distributed/responseprocessor/TopGroupsShardResponseProcessor.java
@@ -179,8 +179,11 @@ public class TopGroupsShardResponseProcessor implements ShardResponseProcessor {
         for (GroupDocs<BytesRef> group : topGroups.groups) {
           for (ScoreDoc scoreDoc : group.scoreDocs) {
             ShardDoc solrDoc = (ShardDoc) scoreDoc;
-            solrDoc.positionInResponse = i++;
-            resultIds.put(solrDoc.id, solrDoc);
+            // Include the first if there are duplicate IDs
+            if ( ! resultIds.containsKey(solrDoc.id)) {
+              solrDoc.positionInResponse = i++;
+              resultIds.put(solrDoc.id, solrDoc);
+            }
           }
         }
       }
diff --git a/solr/core/src/test/org/apache/solr/TestHighlightDedupGrouping.java b/solr/core/src/test/org/apache/solr/TestHighlightDedupGrouping.java
new file mode 100644
index 00000000000..39db914281b
--- /dev/null
+++ b/solr/core/src/test/org/apache/solr/TestHighlightDedupGrouping.java
@@ -0,0 +1,113 @@
+package org.apache.solr;
+
+import org.apache.lucene.util._TestUtil;
+import org.apache.solr.client.solrj.SolrServerException;
+import org.apache.solr.client.solrj.response.QueryResponse;
+import org.apache.solr.common.SolrInputDocument;
+
+import java.io.IOException;
+
+/**
+ * Tests that highlighting doesn't break on grouped documents
+ * with duplicate unique key fields stored on multiple shards.
+ */
+public class TestHighlightDedupGrouping extends BaseDistributedSearchTestCase {
+
+  private static final String id_s1 = "id_s1"; // string copy of the id for highlighting
+  private static final String group_ti1 = "group_ti1";
+  private static final String shard_i1 = "shard_i1";
+
+  public TestHighlightDedupGrouping() {
+    super();
+    fixShardCount = true;
+    shardCount = 2;
+  }
+
+  @Override
+  public void doTest() throws Exception {
+    basicTest();
+    randomizedTest();
+  }
+
+  private void basicTest() throws Exception {
+    del("*:*");
+    commit();
+
+    handle.clear();
+    handle.put("QTime", SKIPVAL);
+    handle.put("timestamp", SKIPVAL);
+    handle.put("grouped", UNORDERED);   // distrib grouping doesn't guarantee order of top level group commands
+
+    int docid = 1;
+    int group = 5;
+    for (int shard = 0 ; shard < shardCount ; ++shard) {
+      addDoc(docid, group, shard); // add the same doc to both shards
+      clients.get(shard).commit();
+    }
+
+    QueryResponse rsp = queryServer(params
+        ("q",           id_s1 + ":" + docid,
+         "shards",      shards,
+         "group",       "true",
+         "group.field", id_s1,
+         "group.limit", Integer.toString(shardCount),
+         "hl",          "true",
+         "hl.fl",       id_s1
+        ));
+
+    // The number of highlit documents should be the same as the de-duplicated docs
+    assertEquals(1, rsp.getHighlighting().values().size());
+  }
+
+  private void randomizedTest() throws Exception {
+    del("*:*");
+    commit();
+
+    handle.clear();
+    handle.put("QTime", SKIPVAL);
+    handle.put("timestamp", SKIPVAL);
+    handle.put("grouped", UNORDERED);   // distrib grouping doesn't guarantee order of top level group commands
+
+    int numDocs = _TestUtil.nextInt(random(), 100, 1000);
+    int numGroups = _TestUtil.nextInt(random(), 1, numDocs / 50);
+    int[] docsInGroup = new int[numGroups + 1];
+    int percentDuplicates = _TestUtil.nextInt(random(), 1, 25);
+    for (int docid = 0 ; docid < numDocs ; ++docid) {
+      int group = _TestUtil.nextInt(random(), 1, numGroups);
+      ++docsInGroup[group];
+      boolean makeDuplicate = 0 == _TestUtil.nextInt(random(), 0, numDocs / percentDuplicates);
+      if (makeDuplicate) {
+        for (int shard = 0 ; shard < shardCount ; ++shard) {
+          addDoc(docid, group, shard);
+        }
+      } else {
+        int shard = _TestUtil.nextInt(random(), 0, shardCount - 1);
+        addDoc(docid, group, shard);
+      }
+    }
+    for (int shard = 0 ; shard < shardCount ; ++shard) {
+      clients.get(shard).commit();
+    }
+
+    for (int group = 1 ; group <= numGroups ; ++group) {
+      QueryResponse rsp = queryServer(params
+          ("q", group_ti1 + ":" + group + " AND " + id_s1 + ":[* TO *]", "start", "0", "rows", "" + numDocs,
+           "fl", id_s1 + "," + shard_i1, "sort", id_s1 + " asc", "shards", shards,
+           "group", "true", "group.field", id_s1
+          ,"group.limit", "" + numDocs
+          ,"hl", "true", "hl.fl", "*", "hl.requireFieldMatch", "true"
+          ));
+      // The number of highlit documents should be the same as the de-duplicated docs for this group
+      assertEquals(docsInGroup[group], rsp.getHighlighting().values().size());
+    }
+  }
+
+  private void addDoc(int docid, int group, int shard) throws IOException, SolrServerException {
+    SolrInputDocument doc = new SolrInputDocument();
+    doc.addField(id, docid);
+    doc.addField(id_s1, docid);  // string copy of the id for highlighting
+    doc.addField(group_ti1, group);
+    doc.addField(shard_i1, shard);
+    clients.get(shard).add(doc);
+  }
+}