diff --git a/hbase-server/src/main/java/org/apache/hadoop/hbase/mapreduce/PutSortReducer.java b/hbase-server/src/main/java/org/apache/hadoop/hbase/mapreduce/PutSortReducer.java
index 5533badfb25..a71b66a2f53 100644
--- a/hbase-server/src/main/java/org/apache/hadoop/hbase/mapreduce/PutSortReducer.java
+++ b/hbase-server/src/main/java/org/apache/hadoop/hbase/mapreduce/PutSortReducer.java
@@ -66,12 +66,11 @@ public class PutSortReducer extends
         for (List<Cell> cells: p.getFamilyCellMap().values()) {
           for (Cell cell: cells) {
             KeyValue kv = KeyValueUtil.ensureKeyValueTypeForMR(cell);
-            map.add(kv);
+            if (map.add(kv)) {// don't count duplicated kv into size
+              curSize += kv.heapSize();
+            }
           }
         }
-        for(KeyValue kv: map){
-          curSize +=kv.heapSize();
-        }
       }
       context.setStatus("Read " + map.size() + " entries of " + map.getClass()
           + "(" + StringUtils.humanReadableInt(curSize) + ")");