diff --git a/odoo/addons/base/ir/ir_translation.py b/odoo/addons/base/ir/ir_translation.py
index ec193543d3d36..b58ce388977a1 100644
--- a/odoo/addons/base/ir/ir_translation.py
+++ b/odoo/addons/base/ir/ir_translation.py
@@ -160,11 +160,18 @@ def finish(self):
                        (tuple(src_relevant_fields), tuple(src_relevant_fields)))
 
         # Step 3: insert new translations
-        cr.execute(""" INSERT INTO %s(name, lang, res_id, src, type, value, module, state, comments)
+        cr.execute(""" INSERT INTO %(_model_table)s(name, lang, res_id, src, type, value, module, state, comments)
                        SELECT name, lang, res_id, src, type, value, module, state, comments
-                       FROM %s AS ti
-                       WHERE NOT EXISTS(SELECT 1 FROM ONLY %s AS irt WHERE %s);
-                   """ % (self._model_table, self._table, self._model_table, find_expr),
+                       FROM %(_table)s AS ti
+                       WHERE NOT EXISTS(SELECT 1 FROM ONLY %(_model_table)s AS irt WHERE %(find_expr)s) AND
+                             NOT EXISTS(SELECT 1 FROM ONLY %(_model_table)s AS irt
+                                        WHERE (irt.type, irt.name, irt.lang, irt.res_id, md5(irt.src)) =
+                                                  (ti.type, ti.name, ti.lang, ti.res_id, md5(ti.src))) AND
+                             NOT EXISTS(SELECT 1 FROM %(_table)s AS tj
+                                        WHERE (tj.type, tj.name, tj.lang, tj.res_id, md5(tj.src)) =
+                                                   (ti.type, ti.name, ti.lang, ti.res_id, md5(ti.src)) AND
+                                              tj.id > ti.id);
+                   """ % dict(_model_table=self._model_table, _table=self._table, find_expr=find_expr),
                    (tuple(src_relevant_fields), tuple(src_relevant_fields)))
 
         if self._debug:
@@ -281,8 +288,18 @@ def _auto_init(self):
             cr.execute('CREATE INDEX ir_translation_src_md5 ON ir_translation (md5(src))')
             cr.commit()
 
-        if 'ir_translation_ltn' not in indexes:
-            cr.execute('CREATE INDEX ir_translation_ltn ON ir_translation (name, lang, type)')
+        if 'ir_translation_unique' not in indexes:
+            # remove duplicated translations before unique index creation
+            cr.execute('''
+                DELETE FROM ir_translation t
+                USING    (SELECT type, name, lang, res_id, md5(src) AS md5_src, max(id) AS max_id
+                    FROM ir_translation
+                    GROUP BY type, name, lang, res_id, md5(src)
+                    HAVING COUNT(id) > 1) dup
+                WHERE    (t.type, t.name, t.lang, t.res_id, md5(t.src)) = (dup.type, dup.name, dup.lang, dup.res_id, dup.md5_src)
+                    AND t.id <> dup.max_id
+            ''')
+            cr.execute('CREATE UNIQUE INDEX ir_translation_unique ON ir_translation (type, name, lang, res_id, md5(src))')
             cr.commit()
         return res
 
diff --git a/odoo/models.py b/odoo/models.py
index 3c9daa02ce9cd..664a09cb5eca6 100644
--- a/odoo/models.py
+++ b/odoo/models.py
@@ -4151,16 +4151,14 @@ def _generate_translated_field(self, table_alias, field, query):
             # The parenthesis surrounding the select are important, as this is a sub-select.
             # The quotes surrounding `ir_translation` are important as well.
             unique_translation_subselect = """
-                (SELECT DISTINCT ON (res_id) res_id, value
-                 FROM "ir_translation"
-                 WHERE name=%s AND lang=%s AND value!=%s
-                 ORDER BY res_id, id DESC)
+                (SELECT res_id, value FROM "ir_translation"
+                 WHERE name=%s AND lang=%s AND value!='')
             """
             alias, alias_statement = query.add_join(
                 (table_alias, unique_translation_subselect, 'id', 'res_id', field),
                 implicit=False,
                 outer=True,
-                extra_params=["%s,%s" % (self._name, field), self.env.lang, ""],
+                extra_params=["%s,%s" % (self._name, field), self.env.lang],
             )
             return 'COALESCE("%s"."%s", "%s"."%s")' % (alias, 'value', table_alias, field)
         else: