diff --git a/api/src/org/labkey/api/dataiterator/MapDataIterator.java b/api/src/org/labkey/api/dataiterator/MapDataIterator.java
index c1810858df4..18c94db9510 100644
--- a/api/src/org/labkey/api/dataiterator/MapDataIterator.java
+++ b/api/src/org/labkey/api/dataiterator/MapDataIterator.java
@@ -18,6 +18,7 @@
 import org.apache.commons.lang3.StringUtils;
 import org.apache.logging.log4j.Logger;
 import org.jetbrains.annotations.NotNull;
+import org.jetbrains.annotations.Nullable;
 import org.labkey.api.collections.ArrayListMap;
 import org.labkey.api.collections.CaseInsensitiveHashMap;
 import org.labkey.api.collections.CaseInsensitiveTreeSet;
@@ -43,7 +44,24 @@ public interface MapDataIterator extends DataIterator
     Logger LOGGER = LogHelper.getLogger(MapDataIterator.class, "DataIterators backed by Maps");
 
     boolean supportsGetMap();
-    Map<String,Object> getMap();
+    @Nullable Map<String,Object> getMap();
+    default @Nullable Map<String, Object> getMapExcludeExistingRecord()
+    {
+        Map<String, Object> row = getMap();
+        if (null == row)
+            return null;
+
+        if (!row.containsKey(ExistingRecordDataIterator.EXISTING_RECORD_COLUMN_NAME))
+            return row;
+
+        Map<String, Object> rowClean = new CaseInsensitiveHashMap<>(row.size());
+        row.forEach((k, v) -> {
+            if (!ExistingRecordDataIterator.EXISTING_RECORD_COLUMN_NAME.equals(k))
+                rowClean.put(k, v);
+        });
+
+        return rowClean;
+    }
 
     /**
      * wrap an existing DataIterator to add MapDataIterator interface
diff --git a/api/src/org/labkey/api/query/AbstractQueryImportAction.java b/api/src/org/labkey/api/query/AbstractQueryImportAction.java
index 71641555b46..d79e2088c89 100644
--- a/api/src/org/labkey/api/query/AbstractQueryImportAction.java
+++ b/api/src/org/labkey/api/query/AbstractQueryImportAction.java
@@ -30,6 +30,7 @@
 import org.labkey.api.action.SpringActionController;
 import org.labkey.api.attachments.FileAttachmentFile;
 import org.labkey.api.audit.TransactionAuditProvider;
+import org.labkey.api.collections.LabKeyCollectors;
 import org.labkey.api.data.Container;
 import org.labkey.api.data.DbSchema;
 import org.labkey.api.data.DbScope;
@@ -56,6 +57,7 @@
 import org.labkey.api.util.CPUTimer;
 import org.labkey.api.util.FileStream;
 import org.labkey.api.util.FileUtil;
+import org.labkey.api.util.JsonUtil;
 import org.labkey.api.util.PageFlowUtil;
 import org.labkey.api.util.Pair;
 import org.labkey.api.util.Path;
@@ -76,6 +78,7 @@
 import java.io.IOException;
 import java.sql.SQLException;
 import java.util.ArrayList;
+import java.util.Collection;
 import java.util.HashMap;
 import java.util.List;
 import java.util.Map;
@@ -761,6 +764,14 @@ protected JSONObject createSuccessResponse(int rowCount)
         return response;
     }
 
+    public static JSONArray prepareRowsResponse(@NotNull Collection<Map<String, Object>> rows)
+    {
+        return rows.stream()
+                .map(JsonUtil::toMapPreserveNonFinite)
+                .map(JsonUtil::toJsonPreserveNulls)
+                .collect(LabKeyCollectors.toJSONArray());
+    }
+
     @Override
     protected ApiResponseWriter createResponseWriter() throws IOException
     {
diff --git a/api/src/org/labkey/api/query/AbstractQueryUpdateService.java b/api/src/org/labkey/api/query/AbstractQueryUpdateService.java
index 6aaa7f8e4bb..7a768bcb915 100644
--- a/api/src/org/labkey/api/query/AbstractQueryUpdateService.java
+++ b/api/src/org/labkey/api/query/AbstractQueryUpdateService.java
@@ -465,7 +465,7 @@ public boolean next() throws BatchValidationException
                     {
                         boolean ret = super.next();
                         if (ret)
-                            rows.add(((MapDataIterator)_delegate).getMap());
+                            rows.add(((MapDataIterator)_delegate).getMapExcludeExistingRecord());
                         return ret;
                     }
                 };
diff --git a/experiment/src/org/labkey/experiment/api/SampleTypeUpdateServiceDI.java b/experiment/src/org/labkey/experiment/api/SampleTypeUpdateServiceDI.java
index bd8273f8d99..fc931100cb3 100644
--- a/experiment/src/org/labkey/experiment/api/SampleTypeUpdateServiceDI.java
+++ b/experiment/src/org/labkey/experiment/api/SampleTypeUpdateServiceDI.java
@@ -343,7 +343,7 @@ else if (nameObj instanceof Number)
                                     }
                                 }
                                 else
-                                    rows.add(((MapDataIterator) _delegate).getMap());
+                                    rows.add(((MapDataIterator) _delegate).getMapExcludeExistingRecord());
                             }
                             return ret;
                         }
diff --git a/query/src/org/labkey/query/controllers/QueryController.java b/query/src/org/labkey/query/controllers/QueryController.java
index 874f0a0ad70..ecec0cbb7d6 100644
--- a/query/src/org/labkey/query/controllers/QueryController.java
+++ b/query/src/org/labkey/query/controllers/QueryController.java
@@ -4739,10 +4739,7 @@ protected JSONObject executeJson(JSONObject json, CommandType commandType, boole
                 }
                 else if (commandType != CommandType.importRows)
                 {
-                    response.put("rows", responseRows.stream()
-                        .map(JsonUtil::toMapPreserveNonFinite)
-                        .map(JsonUtil::toJsonPreserveNulls)
-                        .collect(LabKeyCollectors.toJSONArray()));
+                    response.put("rows", AbstractQueryImportAction.prepareRowsResponse(responseRows));
                 }
 
                 // if there is any provenance information, save it here