1 files changed, 14 insertions, 0 deletions
diff --git a/xml/xml-analysis-impl/src/com/intellij/xml/util/XmlRefCountHolder.java b/xml/xml-analysis-impl/src/com/intellij/xml/util/XmlRefCountHolder.java
index a5f70c2227dc..a9f91bce7d8b 100644
--- a/xml/xml-analysis-impl/src/com/intellij/xml/util/XmlRefCountHolder.java
+++ b/xml/xml-analysis-impl/src/com/intellij/xml/util/XmlRefCountHolder.java
@@ -105,10 +105,24 @@ public class XmlRefCountHolder {
       myId2AttributeListMap.put(id, list);
     }
     else if (!soft) {
+      final boolean html = HtmlUtil.isHtmlFile(attributeValue);
+      final boolean html5 = HtmlUtil.isHtml5Context(attributeValue);
+
       // mark as duplicate
       List<XmlAttributeValue> notSoft = ContainerUtil.mapNotNull(list, new NullableFunction<Pair<XmlAttributeValue, Boolean>, XmlAttributeValue>() {
         @Override
         public XmlAttributeValue fun(Pair<XmlAttributeValue, Boolean> pair) {
+          if (html5 && !"id".equalsIgnoreCase(((XmlAttribute)pair.first.getParent()).getName())) {
+            // according to HTML 5 (http://www.w3.org/TR/html5/dom.html#the-id-attribute) spec
+            // only id attribute is unique identifier
+            return null;
+          }
+          if (html && pair.first.getParent().getParent() == attributeValue.getParent().getParent()) {
+            // according to HTML 4 (http://www.w3.org/TR/html401/struct/global.html#adef-id,
+            // http://www.w3.org/TR/html401/struct/links.html#h-12.2.3) spec id and name occupy
+            // same namespace, but having same values on one tag is ok
+            return null;
+          }
           return pair.second ? null : pair.first;
         }
       });