Index: src/test/org/apache/lucene/index/TestIndexWriterDelete.java
===================================================================
--- src/test/org/apache/lucene/index/TestIndexWriterDelete.java	(revision 509741)
+++ src/test/org/apache/lucene/index/TestIndexWriterDelete.java	(working copy)
@@ -69,6 +69,7 @@
 
     for (int i = 0; i < 7; i++) {
       addDoc(modifier, ++id, value);
+      addDoc(modifier, ++id, value+1);
     }
     modifier.flush();
 
@@ -76,11 +77,11 @@
     assertTrue(0 < modifier.getSegmentCount());
 
     IndexReader reader = IndexReader.open(dir);
-    assertEquals(7, reader.numDocs());
+    assertEquals(14, reader.numDocs());
     reader.close();
 
-    modifier.deleteDocuments(new Term("value", String.valueOf(value)));
-    modifier.deleteDocuments(new Term("value", String.valueOf(value)));
+    modifier.deleteDocuments(new Term("value", String.valueOf(value)));   // delete half
+    modifier.deleteDocuments(new Term("value", String.valueOf(value+1))); // delete other half (should cause a flush)
 
     reader = IndexReader.open(dir);
     assertEquals(0, reader.numDocs());
Index: src/java/org/apache/lucene/index/IndexWriter.java
===================================================================
--- src/java/org/apache/lucene/index/IndexWriter.java	(revision 509924)
+++ src/java/org/apache/lucene/index/IndexWriter.java	(working copy)
@@ -1726,10 +1726,11 @@
     Num num = (Num) bufferedDeleteTerms.get(term);
     if (num == null) {
       bufferedDeleteTerms.put(term, new Num(ramSegmentInfos.size()));
-    } else {
+      numBufferedDeleteTerms++;
+    } else if (num.getNum() < ramSegmentInfos.size()){
       num.setNum(ramSegmentInfos.size());
+      numBufferedDeleteTerms++;
     }
-    numBufferedDeleteTerms++;
   }
 
   // Apply buffered delete terms to the segment just flushed from ram