diff --git a/oak-lucene/src/main/java/org/apache/jackrabbit/oak/plugins/index/lucene/LuceneDocumentMaker.java b/oak-lucene/src/main/java/org/apache/jackrabbit/oak/plugins/index/lucene/LuceneDocumentMaker.java
index d97ffea..7752304 100644
--- a/oak-lucene/src/main/java/org/apache/jackrabbit/oak/plugins/index/lucene/LuceneDocumentMaker.java
+++ b/oak-lucene/src/main/java/org/apache/jackrabbit/oak/plugins/index/lucene/LuceneDocumentMaker.java
@@ -285,7 +285,7 @@ public class LuceneDocumentMaker extends FulltextDocumentMaker<Document> {
                         new BytesRef(property.getValue(Type.STRING)));
             }
 
-            if (f != null && includePropertyValue(property, 0, pd)) {
+            if (f != null && doc.getField(f.name()) == null && includePropertyValue(property, 0, pd)) {
                 doc.add(f);
                 fieldAdded = true;
             }
diff --git a/oak-lucene/src/test/java/org/apache/jackrabbit/oak/plugins/index/lucene/FunctionIndexTest.java b/oak-lucene/src/test/java/org/apache/jackrabbit/oak/plugins/index/lucene/FunctionIndexTest.java
index d6656e3..93e23a0 100644
--- a/oak-lucene/src/test/java/org/apache/jackrabbit/oak/plugins/index/lucene/FunctionIndexTest.java
+++ b/oak-lucene/src/test/java/org/apache/jackrabbit/oak/plugins/index/lucene/FunctionIndexTest.java
@@ -35,6 +35,7 @@ import java.util.Set;
 
 import javax.jcr.PropertyType;
 
+import ch.qos.logback.classic.Level;
 import org.apache.jackrabbit.JcrConstants;
 import org.apache.jackrabbit.oak.Oak;
 import org.apache.jackrabbit.oak.api.ContentRepository;
@@ -42,10 +43,12 @@ import org.apache.jackrabbit.oak.api.Result;
 import org.apache.jackrabbit.oak.api.ResultRow;
 import org.apache.jackrabbit.oak.api.Tree;
 import org.apache.jackrabbit.oak.api.Type;
+import org.apache.jackrabbit.oak.commons.junit.LogCustomizer;
 import org.apache.jackrabbit.oak.plugins.index.lucene.util.IndexDefinitionBuilder;
 import org.apache.jackrabbit.oak.plugins.index.nodetype.NodeTypeIndexProvider;
 import org.apache.jackrabbit.oak.plugins.index.property.PropertyIndexEditorProvider;
 import org.apache.jackrabbit.oak.plugins.index.search.FulltextIndexConstants;
+import org.apache.jackrabbit.oak.plugins.index.search.spi.query.FulltextIndex;
 import org.apache.jackrabbit.oak.plugins.memory.MemoryNodeStore;
 import org.apache.jackrabbit.oak.plugins.memory.PropertyStates;
 import org.apache.jackrabbit.oak.InitialContentHelper;
@@ -54,6 +57,8 @@ import org.apache.jackrabbit.oak.spi.commit.Observer;
 import org.apache.jackrabbit.oak.spi.query.QueryIndexProvider;
 import org.apache.jackrabbit.oak.spi.security.OpenSecurityProvider;
 import org.apache.jackrabbit.oak.spi.state.NodeStore;
+import org.hamcrest.core.IsCollectionContaining;
+import org.junit.Assert;
 import org.junit.Test;
 
 import com.google.common.collect.Iterables;
@@ -339,6 +344,95 @@ public class FunctionIndexTest extends AbstractQueryTest {
                 "lucene:test1(/oak:index/test1)", asList("/b", "/c", "/a"));
     }
 
+    // <OAK-8166>
+    @Test
+    public void sameOrderableRelativePropertyWithandWithoutFunction() throws Exception {
+
+        LogCustomizer customLogs = LogCustomizer.forLogger(LuceneIndexEditor.class.getName()).enable(Level.WARN).create();
+        // Create nodes that will be served by the index definition that follows
+        Tree test = root.getTree("/").addChild("test");
+        test.setProperty("jcr:primaryType", "nt:unstructured", Type.NAME);
+
+        Tree a = test.addChild("jcr:content");
+        a.setProperty("jcr:primaryType", "nt:unstructured", Type.NAME);
+
+        Tree b = a.addChild("n");
+
+        b.setProperty("jcr:primaryType", "nt:unstructured", Type.NAME);
+        b.setProperty("foo", "bar");
+
+        root.commit();
+
+        // Index def with same property - ordered - one with function and one without
+        Tree luceneIndex = createIndex("upper", Collections.<String>emptySet());
+        Tree nonFunc = luceneIndex.addChild(FulltextIndexConstants.INDEX_RULES)
+                .addChild("nt:unstructured")
+                .addChild(FulltextIndexConstants.PROP_NODE)
+                .addChild("foo");
+        nonFunc.setProperty(FulltextIndexConstants.PROP_ORDERED,true);
+        nonFunc.setProperty("name", "jcr:content/n/foo");
+
+        Tree func = luceneIndex.getChild(FulltextIndexConstants.INDEX_RULES)
+                .getChild("nt:unstructured")
+                .getChild(FulltextIndexConstants.PROP_NODE)
+                .addChild("testOak");
+        func.setProperty(FulltextIndexConstants.PROP_ORDERED,true);
+        func.setProperty(FulltextIndexConstants.PROP_FUNCTION, "fn:upper-case(jcr:content/n/@foo)");
+
+        // Now do some change in the node that are covered by above index defintion
+        try {
+            customLogs.starting();
+            root.getTree("/").getChild("test").getChild("jcr:content").getChild("n").setProperty("foo","bar2");
+            root.commit();
+            Assert.assertTrue(customLogs.getLogs().size() == 0);
+            Assert.assertFalse(customLogs.getLogs().contains("Failed to index the node [/test]"));
+
+        } finally {
+            customLogs.finished();
+        }
+
+    }
+
+    @Test
+    public void sameOrderablePropertyWithandWithoutFunction() throws Exception{
+        LogCustomizer customLogs = LogCustomizer.forLogger(LuceneIndexEditor.class.getName()).enable(Level.WARN).create();
+        // Create nodes that will be served by the index definition that follows
+        Tree test = root.getTree("/").addChild("test");
+        test.setProperty("jcr:primaryType", "nt:unstructured", Type.NAME);
+
+        test.setProperty("foo", "bar");
+
+        root.commit();
+
+        // Index def with same property - ordered - one with function and one without
+        Tree luceneIndex = createIndex("upper", Collections.<String>emptySet());
+        Tree nonFunc = luceneIndex.addChild(FulltextIndexConstants.INDEX_RULES)
+                .addChild("nt:unstructured")
+                .addChild(FulltextIndexConstants.PROP_NODE)
+                .addChild("foo");
+        nonFunc.setProperty(FulltextIndexConstants.PROP_ORDERED,true);
+        nonFunc.setProperty("name", "foo");
+
+        Tree func = luceneIndex.getChild(FulltextIndexConstants.INDEX_RULES)
+                .getChild("nt:unstructured")
+                .getChild(FulltextIndexConstants.PROP_NODE)
+                .addChild("testOak");
+        func.setProperty(FulltextIndexConstants.PROP_ORDERED,true);
+        func.setProperty(FulltextIndexConstants.PROP_FUNCTION, "fn:upper-case(@foo)");
+
+        // Now do some change in the node that are covered by above index defintion
+        try {
+            customLogs.starting();
+            root.getTree("/").getChild("test").setProperty("foo","bar2");
+            root.commit();
+            Assert.assertFalse(customLogs.getLogs().contains("Failed to index the node [/test]"));
+
+        } finally {
+            customLogs.finished();
+        }
+
+    }
+
 
     protected String explain(String query){
         String explain = "explain " + query;