diff --git a/libreplan-business/src/main/java/org/libreplan/business/orders/daos/IOrderElementDAO.java b/libreplan-business/src/main/java/org/libreplan/business/orders/daos/IOrderElementDAO.java
index 87524d7f2..157425754 100644
--- a/libreplan-business/src/main/java/org/libreplan/business/orders/daos/IOrderElementDAO.java
+++ b/libreplan-business/src/main/java/org/libreplan/business/orders/daos/IOrderElementDAO.java
@@ -87,10 +87,6 @@ public interface IOrderElementDAO extends IIntegrationEntityDAO<OrderElement> {
     OrderElement findUniqueByCodeAnotherTransaction(String code)
             throws InstanceNotFoundException;
 
-    boolean existsOtherOrderElementByCode(OrderElement orderElement);
-
-    boolean existsByCodeAnotherTransaction(OrderElement orderElement);
-
     List<OrderElement> getAll();
 
     public List<OrderElement> findOrderElementsWithExternalCode();
@@ -139,4 +135,7 @@ public interface IOrderElementDAO extends IIntegrationEntityDAO<OrderElement> {
     public List<OrderElement> findByLabelsAndCriteria(Set<Label> labels,
             Set<Criterion> criteria);
 
+    boolean existsByCodeInAnotherOrderAnotherTransaction(
+            OrderElement orderElement);
+
 }
diff --git a/libreplan-business/src/main/java/org/libreplan/business/orders/daos/OrderElementDAO.java b/libreplan-business/src/main/java/org/libreplan/business/orders/daos/OrderElementDAO.java
index fe30ef96f..d07de5b2f 100644
--- a/libreplan-business/src/main/java/org/libreplan/business/orders/daos/OrderElementDAO.java
+++ b/libreplan-business/src/main/java/org/libreplan/business/orders/daos/OrderElementDAO.java
@@ -43,6 +43,7 @@ import org.libreplan.business.common.daos.IntegrationEntityDAO;
 import org.libreplan.business.common.exceptions.InstanceNotFoundException;
 import org.libreplan.business.expensesheet.daos.IExpenseSheetLineDAO;
 import org.libreplan.business.labels.entities.Label;
+import org.libreplan.business.orders.entities.Order;
 import org.libreplan.business.orders.entities.OrderElement;
 import org.libreplan.business.orders.entities.SchedulingDataForVersion;
 import org.libreplan.business.orders.entities.TaskSource;
@@ -257,22 +258,6 @@ public class OrderElementDAO extends IntegrationEntityDAO<OrderElement>
         return findUniqueByCode(code);
     }
 
-    @Override
-    public boolean existsOtherOrderElementByCode(OrderElement orderElement) {
-        try {
-            OrderElement t = findUniqueByCode(orderElement.getCode());
-            return t != null && t != orderElement;
-        } catch (InstanceNotFoundException e) {
-            return false;
-        }
-    }
-
-    @Override
-    @Transactional(readOnly = true, propagation = Propagation.REQUIRES_NEW)
-    public boolean existsByCodeAnotherTransaction(OrderElement orderElement) {
-        return existsOtherOrderElementByCode(orderElement);
-    }
-
     @Override
     public List<OrderElement> getAll() {
         return list(OrderElement.class);
@@ -493,9 +478,11 @@ public class OrderElementDAO extends IntegrationEntityDAO<OrderElement>
             OrderElement orderElementInDB = orderElementsInDB.get(code);
 
             // There's an element in the DB with the same code and it's a
-            // different element
+            // different element in a different order
             if (orderElementInDB != null
-                    && !orderElementInDB.getId().equals(orderElement.getId())) {
+                    && !orderElementInDB.getId().equals(orderElement.getId())
+                    && !orderElementInDB.getOrder().getId()
+                            .equals(orderElement.getOrder().getId())) {
                 return orderElement;
             }
         }
@@ -590,4 +577,30 @@ public class OrderElementDAO extends IntegrationEntityDAO<OrderElement>
                 .setParameterList("ids", orderElementsIds).list();
     }
 
+    @Override
+    @Transactional(readOnly = true, propagation = Propagation.REQUIRES_NEW)
+    public boolean existsByCodeInAnotherOrderAnotherTransaction(
+            OrderElement orderElement) {
+        return existsByCodeInAnotherOrder(orderElement);
+    }
+
+    private boolean existsByCodeInAnotherOrder(OrderElement orderElement) {
+        try {
+            OrderElement found = findUniqueByCode(orderElement.getCode());
+            return !areInTheSameOrder(orderElement, found);
+        } catch (InstanceNotFoundException e) {
+            return false;
+        }
+    }
+
+    private boolean areInTheSameOrder(OrderElement orderElement1,
+            OrderElement orderElement2) {
+        Order order1 = orderElement1.getOrder();
+        Order order2 = orderElement2.getOrder();
+        if (order1.getId() == null || order2.getId() == null) {
+            return false;
+        }
+        return order1.getId().equals(order2.getId());
+    }
+
 }
\ No newline at end of file
diff --git a/libreplan-business/src/main/java/org/libreplan/business/orders/entities/Order.java b/libreplan-business/src/main/java/org/libreplan/business/orders/entities/Order.java
index d67d15f36..11de57b17 100644
--- a/libreplan-business/src/main/java/org/libreplan/business/orders/entities/Order.java
+++ b/libreplan-business/src/main/java/org/libreplan/business/orders/entities/Order.java
@@ -675,4 +675,20 @@ public class Order extends OrderLineGroup implements Comparable {
         return true;
     }
 
+    @AssertTrue(message = "task code is repeated inside the project")
+    public boolean checkConstraintUniqueCodeInsideOrder() {
+        List<String> codes = new ArrayList<String>();
+        codes.add(getCode());
+
+        for (OrderElement child : getAllChildren()) {
+            String childCode = child.getCode();
+            if (codes.contains(childCode)) {
+                return false;
+            }
+            codes.add(childCode);
+        }
+
+        return true;
+    }
+
 }
diff --git a/libreplan-business/src/main/java/org/libreplan/business/orders/entities/OrderElement.java b/libreplan-business/src/main/java/org/libreplan/business/orders/entities/OrderElement.java
index fbcd0a21b..5699c51ab 100644
--- a/libreplan-business/src/main/java/org/libreplan/business/orders/entities/OrderElement.java
+++ b/libreplan-business/src/main/java/org/libreplan/business/orders/entities/OrderElement.java
@@ -34,6 +34,7 @@ import java.util.Map;
 import java.util.Map.Entry;
 import java.util.Set;
 
+import org.apache.commons.lang.StringUtils;
 import org.apache.commons.lang.Validate;
 import org.hibernate.validator.AssertTrue;
 import org.hibernate.validator.InvalidValue;
@@ -1167,6 +1168,16 @@ public abstract class OrderElement extends IntegrationEntity implements
         return true;
     }
 
+    @AssertTrue(message = "code is already used in another project")
+    public boolean checkConstraintCodeRepeatedInAnotherOrder() {
+        if (StringUtils.isBlank(getCode())) {
+            return true;
+        }
+
+        return !Registry.getOrderElementDAO()
+                .existsByCodeInAnotherOrderAnotherTransaction(this);
+    }
+
     @AssertTrue(message = "a label can not be assigned twice in the same branch")
     public boolean checkConstraintLabelNotRepeatedInTheSameBranch() {
         return checkConstraintLabelNotRepeatedInTheSameBranch(new HashSet<Label>());
diff --git a/libreplan-business/src/main/resources/db.changelog-1.3.xml b/libreplan-business/src/main/resources/db.changelog-1.3.xml
index a538a6dec..a4dbcdcdf 100644
--- a/libreplan-business/src/main/resources/db.changelog-1.3.xml
+++ b/libreplan-business/src/main/resources/db.changelog-1.3.xml
@@ -187,4 +187,10 @@
         </update>
     </changeSet>
 
+    <changeSet id="drop-unique-constraint-code-in-order_element" author="mrego">
+        <comment>Drop unique constraint for code in order_element table</comment>
+        <dropUniqueConstraint tableName="order_element"
+            constraintName="order_element_code_key" />
+    </changeSet>
+
 </databaseChangeLog>
diff --git a/libreplan-business/src/main/resources/org/libreplan/business/orders/entities/Orders.hbm.xml b/libreplan-business/src/main/resources/org/libreplan/business/orders/entities/Orders.hbm.xml
index e6d2a28d1..cf8c70b5a 100644
--- a/libreplan-business/src/main/resources/org/libreplan/business/orders/entities/Orders.hbm.xml
+++ b/libreplan-business/src/main/resources/org/libreplan/business/orders/entities/Orders.hbm.xml
@@ -11,7 +11,7 @@
         <component name="infoComponent" class="org.libreplan.business.orders.entities.InfoComponentWithCode">
             <property name="name" access="field" />
             <property name="description" access="field" type="text" />
-            <property name="code" access="field" unique="true" />
+            <property name="code" access="field" />
         </component>
         <property name="initDate" access="field" column="init_date" />
         <property name="deadline" access="field" />