diff -u -r1.8 -r1.9
--- DetectorElementContainer.java	12 Jul 2007 04:41:14 -0000	1.8
+++ DetectorElementContainer.java	24 Jul 2007 21:56:53 -0000	1.9
@@ -83,13 +83,13 @@

         
         if (de.getIdentifier() != null)
         {

-            if (find(de.getIdentifier()).size() > 0)

+        	IDetectorElementContainer lookup = find(de.getIdentifier());
+            if (find(de.getIdentifier()).size() > 0 && !lookup.contains(de))

             {

-                throw new IllegalArgumentException("Duplicate identifier <"+de.getIdentifier().toString()+">.");

+                throw new IllegalArgumentException("Cannot add DetectorElement <" + de.getName() + ">. Identifier <"+de.getIdentifier().toHexString()+"> is already assigned to <"+this.find(de.getIdentifier()).get(0).getName()+">.");

             }
         }       
         

-        super.add(de);
-        return true;

+        return super.add(de);

     }
 }