diff --git a/navalplanner-business/src/main/java/org/navalplanner/business/orders/daos/HoursGroupDAO.java b/navalplanner-business/src/main/java/org/navalplanner/business/orders/daos/HoursGroupDAO.java
index 1f231bf99..5fc1d0091 100644
--- a/navalplanner-business/src/main/java/org/navalplanner/business/orders/daos/HoursGroupDAO.java
+++ b/navalplanner-business/src/main/java/org/navalplanner/business/orders/daos/HoursGroupDAO.java
@@ -22,6 +22,7 @@ package org.navalplanner.business.orders.daos;
 
 import org.apache.commons.lang.Validate;
 import org.hibernate.Criteria;
+import org.hibernate.HibernateException;
 import org.hibernate.criterion.Restrictions;
 import org.navalplanner.business.common.daos.GenericDAOHibernate;
 import org.navalplanner.business.common.exceptions.InstanceNotFoundException;
@@ -72,7 +73,13 @@ public class HoursGroupDAO extends GenericDAOHibernate<HoursGroup, Long>
         Criteria c = getSession().createCriteria(HoursGroup.class);
         c.add(Restrictions.eq("code", hoursGroup.getCode()));
 
-        HoursGroup result = (HoursGroup) c.uniqueResult();
+        HoursGroup result;
+        try {
+            result = (HoursGroup) c.uniqueResult();
+        } catch (HibernateException e) {
+            result = (HoursGroup) c.list().get(0);
+        }
+
         if (result == null) {
             throw new InstanceNotFoundException(hoursGroup.getCode(),
                     HoursGroup.class.getName());
diff --git a/navalplanner-business/src/main/java/org/navalplanner/business/orders/entities/Order.java b/navalplanner-business/src/main/java/org/navalplanner/business/orders/entities/Order.java
index 306189c83..6aacba626 100644
--- a/navalplanner-business/src/main/java/org/navalplanner/business/orders/entities/Order.java
+++ b/navalplanner-business/src/main/java/org/navalplanner/business/orders/entities/Order.java
@@ -357,4 +357,19 @@ public class Order extends OrderLineGroup {
         }
     }
 
+    @AssertTrue(message = "some code is repeated between hours group codes")
+    public boolean checkConstraintHoursGroupCodeNotRepeated() {
+        Set<String> codes = new HashSet<String>();
+
+        for (HoursGroup hoursGroup : getHoursGroups()) {
+            String code = hoursGroup.getCode();
+            if (codes.contains(code)) {
+                return false;
+            }
+            codes.add(code);
+        }
+
+        return true;
+    }
+
 }
diff --git a/navalplanner-webapp/src/test/java/org/navalplanner/web/orders/OrderModelTest.java b/navalplanner-webapp/src/test/java/org/navalplanner/web/orders/OrderModelTest.java
index 2858d764f..a5710a741 100644
--- a/navalplanner-webapp/src/test/java/org/navalplanner/web/orders/OrderModelTest.java
+++ b/navalplanner-webapp/src/test/java/org/navalplanner/web/orders/OrderModelTest.java
@@ -305,7 +305,7 @@ public class OrderModelTest {
         result.setCode("code-" + UUID.randomUUID());
 
         HoursGroup hoursGroup = HoursGroup.create(result);
-        hoursGroup.setCode("hoursGroupName");
+        hoursGroup.setCode("hoursGroupCode-" + UUID.randomUUID());
         hoursGroup.setWorkingHours(0);
         result.addHoursGroup(hoursGroup);