diff --git a/activerecord/lib/active_record/autosave_association.rb b/activerecord/lib/active_record/autosave_association.rb
index 7c4e81a617..e178cb4ef2 100644
--- a/activerecord/lib/active_record/autosave_association.rb
+++ b/activerecord/lib/active_record/autosave_association.rb
@@ -260,7 +260,8 @@ module ActiveRecord
         if reflection.options[:autosave]
           association.errors.each do |attribute, message|
             attribute = "#{reflection.name}.#{attribute}"
-            errors[attribute] << message if errors[attribute].empty?
+            errors[attribute] << message
+            errors[attribute].uniq!
           end
         else
           errors.add(reflection.name)
diff --git a/activerecord/test/cases/autosave_association_test.rb b/activerecord/test/cases/autosave_association_test.rb
index 7be605ed95..cc36a6dc5b 100644
--- a/activerecord/test/cases/autosave_association_test.rb
+++ b/activerecord/test/cases/autosave_association_test.rb
@@ -794,6 +794,14 @@ class TestAutosaveAssociationOnAHasOneAssociation < ActiveRecord::TestCase
     assert @pirate.errors[:catchphrase].any?
   end
 
+  def test_should_not_ignore_different_error_messages_on_the_same_attribute
+    Ship.validates_format_of :name, :with => /\w/
+    @pirate.ship.name   = ""
+    @pirate.catchphrase = nil
+    assert @pirate.invalid?
+    assert_equal ["can't be blank", "is invalid"], @pirate.errors[:"ship.name"]
+  end
+
   def test_should_still_allow_to_bypass_validations_on_the_associated_model
     @pirate.catchphrase = ''
     @pirate.ship.name = ''