diff --git a/jedi/api/__init__.py b/jedi/api/__init__.py
index 426f56ec..5f75410b 100644
--- a/jedi/api/__init__.py
+++ b/jedi/api/__init__.py
@@ -318,7 +318,8 @@ class Script(object):
         )
 
         defs = [classes.Definition(self._inference_state, d) for d in set(names)]
-        return helpers.sorted_definitions(defs)
+        # Avoid duplicates
+        return list(set(helpers.sorted_definitions(defs)))
 
     @validate_line_column
     def help(self, line=None, column=None):
diff --git a/test/completion/basic.py b/test/completion/basic.py
index 3ff919ca..b0e71bad 100644
--- a/test/completion/basic.py
+++ b/test/completion/basic.py
@@ -422,3 +422,11 @@ with Foo() as f3:
 #? 6 Foo
 with Foo() as f3:
     f3
+
+# -----------------
+# Avoiding multiple definitions
+# -----------------
+
+some_array = ['', '']
+#! ['def upper']
+some_array[some_not_defined_index].upper