diff --git a/src/main/java/it/geosolutions/geoserver/rest/encoder/GSLayerEncoder21.java b/src/main/java/it/geosolutions/geoserver/rest/encoder/GSLayerEncoder21.java
index b3f5acd..ce29c35 100644
--- a/src/main/java/it/geosolutions/geoserver/rest/encoder/GSLayerEncoder21.java
+++ b/src/main/java/it/geosolutions/geoserver/rest/encoder/GSLayerEncoder21.java
@@ -25,7 +25,9 @@
 
 package it.geosolutions.geoserver.rest.encoder;
 
+import java.util.ArrayList;
 import java.util.HashMap;
+import java.util.List;
 import java.util.Map;
 import java.util.Map.Entry;
 
@@ -49,7 +51,7 @@ public class GSLayerEncoder21 extends GSLayerEncoder {
 	public final static String METADATA = "metadata";
 	final private GSMetadataEncoder metadata = new GSMetadataEncoder();
 	public Map<String, String> authorityURLList;
-	public Map<String, String> identifierList;
+	public Map<String, List<String>> identifierList;
 
 	private class GSMetadataEncoder extends NestedElementEncoder {
 		public GSMetadataEncoder() {
@@ -125,11 +127,14 @@ public class GSLayerEncoder21 extends GSLayerEncoder {
 			if (authorityURLList.containsKey(authorityURL)) {
 				identifierList.remove(authorityURL);
 				String jsonStr = "";
-				for (Entry<String, String> entry : identifierList.entrySet()) {
-					jsonStr += "{" + "\"" + AuthorityURLInfo.name.name()
-							+ "\":\"" + entry.getValue() + "\"," + "\""
-							+ AuthorityURLInfo.href.name() + "\":\""
-							+ entry.getKey() + "\"" + "},";
+				for (Entry<String, List<String>> entry : identifierList
+						.entrySet()) {
+					for (String value : entry.getValue()) {
+						jsonStr += "{" + "\"" + AuthorityURLInfo.name.name()
+								+ "\":\"" + value + "\"," + "\""
+								+ AuthorityURLInfo.href.name() + "\":\""
+								+ entry.getKey() + "\"" + "},";
+					}
 				}
 				metadata.set("identifiers", "[" + jsonStr + "]");
 				delete = true;
@@ -145,16 +150,29 @@ public class GSLayerEncoder21 extends GSLayerEncoder {
 	 */
 	public void addIdentifier(GSIdentifierInfoEncoder identifierInfo) {
 		if (identifierList == null) {
-			identifierList = new HashMap<String, String>();
+			identifierList = new HashMap<String, List<String>>();
 		}
-		identifierList.put(identifierInfo.getAuthority(),
-				identifierInfo.getIdentifier());
+		
+		String authority = identifierInfo.getAuthority();
+
+		if (!identifierList.containsKey(authority)) {
+			List<String> ids = new ArrayList<String>();
+			ids.add(identifierInfo.getIdentifier());
+			identifierList.put(authority, ids);
+		} else {
+			List<String> ids = identifierList.get(authority);
+			ids.add(identifierInfo.getIdentifier());
+			identifierList.put(authority, ids);
+		}
+
 		String jsonStr = "";
-		for (Entry<String, String> entry : identifierList.entrySet()) {
-			jsonStr += "{" + "\"" + IdentifierInfo.authority.name() + "\":\""
-					+ entry.getKey() + "\"," + "\""
-					+ IdentifierInfo.identifier.name() + "\":\""
-					+ entry.getValue() + "\"" + "},";
+		for (Entry<String, List<String>> entry : identifierList.entrySet()) {
+			for (String value : entry.getValue()) {
+				jsonStr += "{" + "\"" + IdentifierInfo.authority.name()
+						+ "\":\"" + entry.getKey() + "\"," + "\""
+						+ IdentifierInfo.identifier.name() + "\":\"" + value
+						+ "\"" + "},";
+			}
 		}
 		metadata.set("identifiers", "[" + jsonStr + "]");
 	}
@@ -172,11 +190,14 @@ public class GSLayerEncoder21 extends GSLayerEncoder {
 			if (identifierList.containsKey(authority)) {
 				identifierList.remove(authority);
 				String jsonStr = "";
-				for (Entry<String, String> entry : identifierList.entrySet()) {
-					jsonStr += "{" + "\"" + IdentifierInfo.authority.name()
-							+ "\":\"" + entry.getKey() + "\"," + "\""
-							+ IdentifierInfo.identifier.name() + "\":\""
-							+ entry.getValue() + "\"" + "},";
+				for (Entry<String, List<String>> entry : identifierList
+						.entrySet()) {
+					for (String value : entry.getValue()) {
+						jsonStr += "{" + "\"" + IdentifierInfo.authority.name()
+								+ "\":\"" + entry.getKey() + "\"," + "\""
+								+ IdentifierInfo.identifier.name() + "\":\""
+								+ value + "\"" + "},";
+					}
 				}
 				metadata.set("identifiers", "[" + jsonStr + "]");
 				delete = true;
diff --git a/src/test/java/it/geosolutions/geoserver/rest/encoder/GSLayerEncoder21Test.java b/src/test/java/it/geosolutions/geoserver/rest/encoder/GSLayerEncoder21Test.java
index cdd49e0..c714283 100644
--- a/src/test/java/it/geosolutions/geoserver/rest/encoder/GSLayerEncoder21Test.java
+++ b/src/test/java/it/geosolutions/geoserver/rest/encoder/GSLayerEncoder21Test.java
@@ -53,6 +53,8 @@ public class GSLayerEncoder21Test {
 				"authority2", "http://www.authority2.org"));
 		layerEncoder.addIdentifier(new GSIdentifierInfoEncoder("authority2",
 				"identifier2"));
+		layerEncoder.addIdentifier(new GSIdentifierInfoEncoder("authority2",
+				"additionalId"));
 	}
 
 	@Test
@@ -116,10 +118,18 @@ public class GSLayerEncoder21Test {
 				String[] kvp2_2 = props2[1].split("\":");
 				Assert.assertEquals(IdentifierInfo.authority.name(),
 						kvp2_1[0].replace("\"", ""));
-				Assert.assertEquals("authority1", kvp2_1[1].replace("\"", ""));
+				Assert.assertEquals("authority2", kvp2_1[1].replace("\"", ""));
 				Assert.assertEquals(IdentifierInfo.identifier.name(),
 						kvp2_2[0].replace("\"", ""));
-				Assert.assertEquals("identifier1", kvp2_2[1].replace("\"", ""));
+				Assert.assertEquals("additionalId", kvp2_2[1].replace("\"", ""));
+				
+				String[] props3 = items[2].split(",");
+		        String[] kvp3_1 = props3[0].split("\":");
+		        String[] kvp3_2 = props3[1].split("\":");
+		        Assert.assertEquals(IdentifierInfo.authority.name(), kvp3_1[0].replace("\"", ""));
+		        Assert.assertEquals("authority1", kvp3_1[1].replace("\"", ""));
+		        Assert.assertEquals(IdentifierInfo.identifier.name(), kvp3_2[0].replace("\"", ""));
+		        Assert.assertEquals("identifier1", kvp3_2[1].replace("\"", ""));
 
 			}
 		}
diff --git a/src/test/java/it/geosolutions/geoserver/rest/encoder/feature/GSFeatureEncoderTest.java b/src/test/java/it/geosolutions/geoserver/rest/encoder/feature/GSFeatureEncoderTest.java
index 7ab4b0f..1d8e245 100644
--- a/src/test/java/it/geosolutions/geoserver/rest/encoder/feature/GSFeatureEncoderTest.java
+++ b/src/test/java/it/geosolutions/geoserver/rest/encoder/feature/GSFeatureEncoderTest.java
@@ -113,9 +113,12 @@ public class GSFeatureEncoderTest extends GeoserverRESTPublisherTest {
 		layerEncoder.addAuthorityURL(authorityURL);
 
 		// identifier
-		GSIdentifierInfoEncoder identifier = new GSIdentifierInfoEncoder(
+		GSIdentifierInfoEncoder identifier1 = new GSIdentifierInfoEncoder(
 				"authority1", "identifier1");
-		layerEncoder.addIdentifier(identifier);
+		GSIdentifierInfoEncoder identifier2 = new GSIdentifierInfoEncoder(
+				"authority1", "another_identifier");
+		layerEncoder.addIdentifier(identifier1);
+		layerEncoder.addIdentifier(identifier2);
         
         publisher.createWorkspace(DEFAULT_WS);