diff --git a/navalplanner-business/src/main/java/org/navalplanner/business/advance/entities/AdvanceType.java b/navalplanner-business/src/main/java/org/navalplanner/business/advance/entities/AdvanceType.java
index d7a9302f0..496473565 100644
--- a/navalplanner-business/src/main/java/org/navalplanner/business/advance/entities/AdvanceType.java
+++ b/navalplanner-business/src/main/java/org/navalplanner/business/advance/entities/AdvanceType.java
@@ -123,4 +123,10 @@ public class AdvanceType {
         return true;
     }
 
+    public static boolean equivalentInDB(AdvanceType type, AdvanceType otherType) {
+        if (type.getId() == null || otherType.getId() == null)
+            return false;
+        return type.getId().equals(otherType.getId());
+    }
+
 }
diff --git a/navalplanner-business/src/main/java/org/navalplanner/business/orders/entities/OrderElement.java b/navalplanner-business/src/main/java/org/navalplanner/business/orders/entities/OrderElement.java
index 43c0a056c..7db89cfb0 100644
--- a/navalplanner-business/src/main/java/org/navalplanner/business/orders/entities/OrderElement.java
+++ b/navalplanner-business/src/main/java/org/navalplanner/business/orders/entities/OrderElement.java
@@ -8,6 +8,7 @@ import java.util.Set;
 
 import org.hibernate.validator.NotEmpty;
 import org.navalplanner.business.advance.entities.AdvanceAssigment;
+import org.navalplanner.business.advance.entities.AdvanceType;
 import org.navalplanner.business.advance.exceptions.DuplicateAdvanceAssigmentForOrderElementException;
 import org.navalplanner.business.advance.exceptions.DuplicateValueTrueReportGlobalAdvanceException;
 import org.navalplanner.business.planner.entities.TaskElement;
@@ -209,8 +210,8 @@ public abstract class OrderElement {
             throws DuplicateAdvanceAssigmentForOrderElementException {
         for (AdvanceAssigment advanceAssigment : orderElement
                 .getAdvanceAssigments()) {
-            if (advanceAssigment.getAdvanceType().getId().equals(
-                    newAdvanceAssigment.getAdvanceType().getId())) {
+            if (AdvanceType.equivalentInDB(advanceAssigment.getAdvanceType(),
+                    newAdvanceAssigment.getAdvanceType())) {
                 throw new DuplicateAdvanceAssigmentForOrderElementException(
                         "Duplicate Advance Assigment For Order Element", this,
                         OrderElement.class);