no duplicates in java var name suggestions

java/java-impl/src/com/intellij/codeInsight/completion/JavaMemberNameCompletionContributor.java

@@ -361,11 +361,18 @@ public class JavaMemberNameCompletionContributor extends CompletionContributor {
   }
 
   private static void addLookupItems(Set<LookupElement> lookupElements, @Nullable final SuggestedNameInfo callback, PrefixMatcher matcher, String... strings) {
+    outer:
     for (int i = 0; i < strings.length; i++) {
       String name = strings[i];
       if (!matcher.prefixMatches(name)) {
         continue;
       }
+
+      for (LookupElement lookupElement : lookupElements) {
+        if (lookupElement.getAllLookupStrings().contains(name)) {
+          continue outer;
+        }
+      }
       
       LookupElement element = PrioritizedLookupElement.withPriority(LookupElementBuilder.create(name).withAutoCompletionPolicy(AutoCompletionPolicy.GIVE_CHANCE_TO_OVERWRITE), -i);
       if (callback != null) {

java/java-tests/testData/codeInsight/completion/variables/DuplicateSuggestionsFromUsage.java

@@ -0,0 +1,11 @@
+public class Foo {
+
+  void bar() {
+    APreferencePolicy p<caret> = 2;
+    System.out.println(policy);
+  }
+}
+
+class APreferencePolicy {
+
+}

java/java-tests/testSrc/com/intellij/codeInsight/completion/VariablesCompletionTest.groovy

@@ -157,4 +157,9 @@ public class VariablesCompletionTest extends LightFixtureCompletionTestCase {
     assertStringItems("stringBuffer", "buffer");
   }
 
+  public void testDuplicateSuggestionsFromUsage() {
+    configureByFile(FILE_PREFIX + getTestName(false) + ".java");
+    assertStringItems("preferencePolicy", "policy");
+  }
+
 }