diff --git a/core/modules/taxonomy/taxonomy.module b/core/modules/taxonomy/taxonomy.module
index eb20c26..9b490d8 100644
--- a/core/modules/taxonomy/taxonomy.module
+++ b/core/modules/taxonomy/taxonomy.module
@@ -1710,6 +1710,15 @@ function taxonomy_rdf_mapping() {
 function taxonomy_field_presave($entity_type, $entity, $field, $instance, $langcode, &$items) {
   foreach ($items as $delta => $item) {
     if ($item['tid'] == 'autocreate') {
+      // Avoid duplicating tags within the same vocabulary.
+      $tid = db_query_range("SELECT tid FROM {taxonomy_term_data} WHERE name = :name AND vid = :vid", 0, 1, array(
+        ':name' => trim($item['name']),
+        ':vid' => $item['vid'],
+      ))->fetchField();
+      if (!empty($tid)) {
+        $items[$delta]['tid'] = $tid;
+        continue;
+      }
       $term = (object) $item;
       unset($term->tid);
       taxonomy_term_save($term);
diff --git a/core/modules/taxonomy/taxonomy.test b/core/modules/taxonomy/taxonomy.test
index 747d822..bbb5df5 100644
--- a/core/modules/taxonomy/taxonomy.test
+++ b/core/modules/taxonomy/taxonomy.test
@@ -829,6 +829,124 @@ class TaxonomyTermTestCase extends TaxonomyWebTestCase {
 }
 
 /**
+ * Tests term autocreation with multiple autocomplete widgets.
+ */
+class TaxonomyTermAutocreateTestCase extends TaxonomyWebTestCase {
+
+  public static function getInfo() {
+    return array(
+      'name' => 'Taxonomy term autocreation',
+      'description' => 'Tests term autocreation with multiple autocomplete widgets.',
+      'group' => 'Taxonomy',
+    );
+  }
+
+  function setUp() {
+    parent::setUp('taxonomy');
+    // Create an administrative user.
+    $this->admin_user = $this->drupalCreateUser(array('administer taxonomy', 'bypass node access'));
+    $this->drupalLogin($this->admin_user);
+
+    // Create a vocabulary and add two autocomplete fields on article nodes.
+    $this->vocabulary = $this->createVocabulary();
+
+    $this->field_name_1 = drupal_strtolower($this->randomName());
+    $this->field_1 = array(
+      'field_name' => $this->field_name_1,
+      'type' => 'taxonomy_term_reference',
+      'cardinality' => FIELD_CARDINALITY_UNLIMITED,
+      'settings' => array(
+        'allowed_values' => array(
+          array(
+            'vocabulary' => $this->vocabulary->machine_name,
+            'parent' => 0,
+          ),
+        ),
+      ),
+    );
+    field_create_field($this->field_1);
+    $this->instance_1 = array(
+      'field_name' => $this->field_name_1,
+      'bundle' => 'article',
+      'entity_type' => 'node',
+      'widget' => array(
+        'type' => 'taxonomy_autocomplete',
+      ),
+      'display' => array(
+        'default' => array(
+          'type' => 'taxonomy_term_reference_link',
+        ),
+      ),
+    );
+    field_create_instance($this->instance_1);
+
+    $this->field_name_2 = drupal_strtolower($this->randomName());
+    $this->field_2 = array(
+      'field_name' => $this->field_name_2,
+      'type' => 'taxonomy_term_reference',
+      'cardinality' => FIELD_CARDINALITY_UNLIMITED,
+      'settings' => array(
+        'allowed_values' => array(
+          array(
+            'vocabulary' => $this->vocabulary->machine_name,
+            'parent' => 0,
+          ),
+        ),
+      ),
+    );
+    field_create_field($this->field_2);
+    $this->instance_2 = array(
+      'field_name' => $this->field_name_2,
+      'bundle' => 'article',
+      'entity_type' => 'node',
+      'widget' => array(
+        'type' => 'taxonomy_autocomplete',
+      ),
+      'display' => array(
+        'default' => array(
+          'type' => 'taxonomy_term_reference_link',
+        ),
+      ),
+    );
+    field_create_instance($this->instance_2);
+  }
+
+  /**
+   * Tests adding the same term to multiple autocomplete fields.
+   */
+  function testTaxonomyTagging() {
+    $term1_name = $this->randomName();
+
+    // Post an article.
+    $edit = array();
+    $langcode = LANGUAGE_NONE;
+    $edit["title"] = $this->randomName();
+    $edit["body[$langcode][0][value]"] = $this->randomName();
+    $edit["{$this->field_name_1}[$langcode]"] = $term1_name;
+    $this->drupalPost('node/add/article', $edit, t('Save'));
+
+    // Check that the term is saved and can be retrieved.
+    $terms = taxonomy_get_term_by_name($term1_name);
+    $this->assertEqual(1, count($terms), t('The term was saved.'));
+
+    // Add a new term to two different fields.
+    $node = $this->drupalGetNodeByTitle($edit["title"]);
+    $term2_name = $this->randomName();
+    $edit["{$this->field_name_1}[$langcode]"] = $term2_name;
+    $edit["{$this->field_name_2}[$langcode]"] = $term2_name;
+    $this->drupalPost('node/' . $node->nid . '/edit', $edit, t('Save'));
+
+    // Check that the term is displayed multiple times.
+    $this->assertText($term2_name, t('The term was saved and appears on the node page.'));
+    $this->assertNoUniqueText($term2_name, t('The term displays multiple times.'));
+
+    // Check that the term is saved only once.
+    $terms = taxonomy_get_term_by_name($term2_name);
+    $this->assertEqual(1, count($terms), t('The term was saved only once.'));
+  }
+}
+
+/**
  * Test the taxonomy_term_load_multiple() function.
  */
 class TaxonomyLoadMultipleUnitTest extends TaxonomyWebTestCase {