diff --git a/NEWS b/NEWS
index cd86dc60..b8f09cfa 100644
--- a/NEWS
+++ b/NEWS
@@ -10,6 +10,7 @@ NEWS ( CHANGELOG and HISTORY )                                     HTMLPurifier
 ==========================
 
 4.8.0, unknown release date
+! %CSS.AllowDuplicates permits duplicate CSS properties.
 - alt truncation could result in malformed UTF-8 sequence. Don't
   truncate.  Thanks Brandon Farber for reporting.
 
diff --git a/library/HTMLPurifier/AttrDef/CSS.php b/library/HTMLPurifier/AttrDef/CSS.php
index 02c1641f..2b977ca3 100644
--- a/library/HTMLPurifier/AttrDef/CSS.php
+++ b/library/HTMLPurifier/AttrDef/CSS.php
@@ -25,6 +25,7 @@ class HTMLPurifier_AttrDef_CSS extends HTMLPurifier_AttrDef
         $css = $this->parseCDATA($css);
 
         $definition = $config->getCSSDefinition();
+        $allow_duplicates = $config->get("CSS.AllowDuplicates");
 
         // we're going to break the spec and explode by semicolons.
         // This is because semicolon rarely appears in escaped form
@@ -34,6 +35,7 @@ class HTMLPurifier_AttrDef_CSS extends HTMLPurifier_AttrDef
 
         $declarations = explode(';', $css);
         $propvalues = array();
+        $new_declarations = '';
 
         /**
          * Name of the current CSS property being validated.
@@ -83,7 +85,11 @@ class HTMLPurifier_AttrDef_CSS extends HTMLPurifier_AttrDef
             if ($result === false) {
                 continue;
             }
-            $propvalues[$property] = $result;
+            if ($allow_duplicates) {
+                $new_declarations .= "$property:$result;";
+            } else {
+                $propvalues[$property] = $result;
+            }
         }
 
         $context->destroy('CurrentCSSProperty');
@@ -92,7 +98,6 @@ class HTMLPurifier_AttrDef_CSS extends HTMLPurifier_AttrDef
         // slightly inefficient, but it's the only way of getting rid of
         // duplicates. Perhaps config to optimize it, but not now.
 
-        $new_declarations = '';
         foreach ($propvalues as $prop => $value) {
             $new_declarations .= "$prop:$value;";
         }
diff --git a/library/HTMLPurifier/ConfigSchema/schema.ser b/library/HTMLPurifier/ConfigSchema/schema.ser
index 1e6ccd22..30785dcf 100644
Binary files a/library/HTMLPurifier/ConfigSchema/schema.ser and b/library/HTMLPurifier/ConfigSchema/schema.ser differ
diff --git a/library/HTMLPurifier/ConfigSchema/schema/CSS.AllowDuplicates.txt b/library/HTMLPurifier/ConfigSchema/schema/CSS.AllowDuplicates.txt
new file mode 100644
index 00000000..4d054b1f
--- /dev/null
+++ b/library/HTMLPurifier/ConfigSchema/schema/CSS.AllowDuplicates.txt
@@ -0,0 +1,11 @@
+CSS.AllowDuplicates
+TYPE: bool
+DEFAULT: false
+VERSION: 4.8.0
+--DESCRIPTION--
+<p>
+  By default, HTML Purifier removes duplicate CSS properties,
+  like <code>color:red; color:blue</code>.  If this is set to
+  true, duplicate properties are allowed.
+</p>
+--# vim: et sw=4 sts=4
diff --git a/tests/HTMLPurifier/AttrDef/CSSTest.php b/tests/HTMLPurifier/AttrDef/CSSTest.php
index 778a22bd..46779154 100644
--- a/tests/HTMLPurifier/AttrDef/CSSTest.php
+++ b/tests/HTMLPurifier/AttrDef/CSSTest.php
@@ -167,6 +167,13 @@ class HTMLPurifier_AttrDef_CSSTest extends HTMLPurifier_AttrDefHarness
         $this->assertDef('z-index:-2;');
     }
 
+    public function testAllowDuplicates()
+    {
+        $this->config->set('CSS.AllowDuplicates', true);
+        $this->assertDef('text-align:right;text-align:left;');
+        $this->assertDef('text-align:right;text-align:left;text-align:right;');
+    }
+
 }
 
 // vim: et sw=4 sts=4