diff --git a/apps/advanced/backend/web/css/site.css b/apps/advanced/backend/web/css/site.css
index 2d27436..bf9d2b2 100644
--- a/apps/advanced/backend/web/css/site.css
+++ b/apps/advanced/backend/web/css/site.css
@@ -43,3 +43,11 @@ a.desc:after { content: /*"\e114"*/"\e152"; }
 
 .sort-ordinal a.asc:after { content: "\e155"; }
 .sort-ordinal a.desc:after { content: "\e156"; }
+
+.error-summary {
+	color: #b94a48;
+	background: #fdf7f7;
+	border-left: 3px solid #eed3d7;
+	padding: 10px 20px;
+	margin: 0 0 15px 0;
+}
diff --git a/apps/advanced/frontend/web/css/site.css b/apps/advanced/frontend/web/css/site.css
index 2d27436..bf9d2b2 100644
--- a/apps/advanced/frontend/web/css/site.css
+++ b/apps/advanced/frontend/web/css/site.css
@@ -43,3 +43,11 @@ a.desc:after { content: /*"\e114"*/"\e152"; }
 
 .sort-ordinal a.asc:after { content: "\e155"; }
 .sort-ordinal a.desc:after { content: "\e156"; }
+
+.error-summary {
+	color: #b94a48;
+	background: #fdf7f7;
+	border-left: 3px solid #eed3d7;
+	padding: 10px 20px;
+	margin: 0 0 15px 0;
+}
diff --git a/apps/basic/web/css/site.css b/apps/basic/web/css/site.css
index d44558d..7a1fb92 100644
--- a/apps/basic/web/css/site.css
+++ b/apps/basic/web/css/site.css
@@ -44,3 +44,11 @@ a.desc:after { content: /*"\e114"*/"\e152"; }
 
 .sort-ordinal a.asc:after { content: "\e155"; }
 .sort-ordinal a.desc:after { content: "\e156"; }
+
+.error-summary {
+	color: #b94a48;
+	background: #fdf7f7;
+	border-left: 3px solid #eed3d7;
+	padding: 10px 20px;
+	margin: 0 0 15px 0;
+}
diff --git a/framework/CHANGELOG.md b/framework/CHANGELOG.md
index 178a482..5a0b7fe 100644
--- a/framework/CHANGELOG.md
+++ b/framework/CHANGELOG.md
@@ -16,10 +16,12 @@ Yii Framework 2 Change Log
 - Bug #1591: StringValidator is accessing undefined property (qiangxue)
 - Bug #1597: Added `enableAutoLogin` to basic and advanced application templates so "remember me" now works properly (samdark)
 - Bug #1631: Charset is now explicitly set to UTF-8 when serving JSON (samdark)
+- Bug #1688: ActiveForm is creating duplicated messages in error summary (qiangxue)
 - Bug: Fixed `Call to a member function registerAssetFiles() on a non-object` in case of wrong `sourcePath` for an asset bundle (samdark)
 - Bug: Fixed incorrect event name for `yii\jui\Spinner` (samdark)
 - Bug: Json::encode() did not handle objects that implement JsonSerializable interface correctly (cebe)
 - Bug: Fixed issue with tabular input on ActiveField::radio() and ActiveField::checkbox() (jom)
+- Enh #364: Improve Inflector::slug with `intl` transliteration. Improved transliteration char map. (tonydspaniard)
 - Enh #797: Added support for validating multiple columns by `UniqueValidator` and `ExistValidator` (qiangxue)
 - Enh #1293: Replaced Console::showProgress() with a better approach. See Console::startProgress() for details (cebe)
 - Enh #1406: DB Schema support for Oracle Database (p0larbeer, qiangxue)
@@ -51,7 +53,6 @@ Yii Framework 2 Change Log
 - Chg: Changed the signature of `urlCreator` and button creators for `yii\gridview\ActionColumn` (qiangxue)
 - New #1438: [MongoDB integration](https://github.com/yiisoft/yii2-mongodb) ActiveRecord and Query (klimov-paul)
 - New #1393: [Codeception testing framework integration](https://github.com/yiisoft/yii2-codeception) (Ragazzo)
-- Enh #364: Improve Inflector::slug with `intl` transliteration. Improved transliteration char map. (tonydspaniard)
 
 2.0.0 alpha, December 1, 2013
 ---------------------------
diff --git a/framework/yii/assets/yii.activeForm.js b/framework/yii/assets/yii.activeForm.js
index e898efc..d4fc877 100644
--- a/framework/yii/assets/yii.activeForm.js
+++ b/framework/yii/assets/yii.activeForm.js
@@ -365,7 +365,7 @@
 	var updateSummary = function ($form, messages) {
 		var data = $form.data('yiiActiveForm'),
 			$summary = $form.find(data.settings.errorSummary),
-			$ul = $summary.find('ul');
+			$ul = $summary.find('ul').html('');
 
 		if ($summary.length && messages) {
 			$.each(data.attributes, function () {