diff --git a/odoo/addons/base/models/ir_translation.py b/odoo/addons/base/models/ir_translation.py
index 0ad132d4c33..4ec7c98cf3a 100644
--- a/odoo/addons/base/models/ir_translation.py
+++ b/odoo/addons/base/models/ir_translation.py
@@ -616,6 +616,14 @@ class IrTranslation(models.Model):
                             SELECT 1 FROM ir_translation
                             WHERE lang=l.code AND type='model' AND name=%(name)s AND res_id=%(res_id)s
                         );
+
+                        DELETE FROM ir_translation dup
+                        WHERE type='model' AND name=%(name)s AND res_id=%(res_id)s
+                            AND dup.id NOT IN (SELECT MAX(t.id)
+                                       FROM ir_translation t
+                                       WHERE t.lang=dup.lang AND type='model' AND name=%(name)s AND res_id=%(res_id)s
+                            );
+
                         UPDATE ir_translation SET src=%(src)s
                         WHERE type='model' AND name=%(name)s AND res_id=%(res_id)s;
                     """
diff --git a/odoo/addons/base/tests/test_translate.py b/odoo/addons/base/tests/test_translate.py
index 5bd33a4852f..e8a76b12c86 100644
--- a/odoo/addons/base/tests/test_translate.py
+++ b/odoo/addons/base/tests/test_translate.py
@@ -275,6 +275,37 @@ class TestTranslation(TransactionCase):
         self.assertEqual(categories.ids, [padawans.id, self.customers.id],
             "Search ordered by translated name should return Padawans (Apprentis) before Customers (Clients)")
 
+    def test_105_duplicated_translation(self):
+        """ Test synchronizing translations with duplicated source """
+        # create a category with a French translation
+        padawans = self.env['res.partner.category'].create({'name': 'Padawan'})
+        self.env['ir.translation'].create({
+            'type': 'model',
+            'name': 'res.partner.category,name',
+            'module':'base',
+            'lang': 'fr_FR',
+            'res_id': padawans.id,
+            'value': 'Apprenti',
+            'state': 'translated',
+        })
+        # change name and insert a duplicate manually
+        padawans.write({'name': 'Padawans'})
+        self.env['ir.translation'].create({
+            'type': 'model',
+            'name': 'res.partner.category,name',
+            'module':'base',
+            'lang': 'fr_FR',
+            'res_id': padawans.id,
+            'value': 'Apprentis',
+            'state': 'translated',
+        })
+        self.env['ir.translation'].translate_fields('res.partner.category', padawans.id, 'name')
+        translations = self.env['ir.translation'].search([
+            ('res_id', '=', padawans.id), ('name', '=', 'res.partner.category,name')
+        ])
+        self.assertEqual(len(translations), 1, "Translations were not merged after `translate_fields` call")
+        self.assertEqual(translations.value, "Apprentis", "The most recent translation must stay")
+
 
 class TestXMLTranslation(TransactionCase):
     def setUp(self):