diff --git a/src/java/com/threerings/presents/dobj/DObject.java b/src/java/com/threerings/presents/dobj/DObject.java
index 58df1fc53..8ca776ed6 100644
--- a/src/java/com/threerings/presents/dobj/DObject.java
+++ b/src/java/com/threerings/presents/dobj/DObject.java
@@ -1,5 +1,5 @@
 //
-// $Id: DObject.java,v 1.64 2003/05/22 17:23:53 mdb Exp $
+// $Id: DObject.java,v 1.65 2003/07/20 17:02:26 mdb Exp $
 
 package com.threerings.presents.dobj;
 
@@ -792,7 +792,9 @@ public class DObject implements Streamable
             // immediately
             boolean alreadyApplied = false;
             if (_omgr != null && _omgr.isManager(this)) {
-                set.add(entry);
+                if (!set.add(entry)) {
+                    Thread.dumpStack();
+                }
                 alreadyApplied = true;
             }
             // dispatch an entry added event
diff --git a/src/java/com/threerings/presents/dobj/EntryAddedEvent.java b/src/java/com/threerings/presents/dobj/EntryAddedEvent.java
index b19033026..f9392efb8 100644
--- a/src/java/com/threerings/presents/dobj/EntryAddedEvent.java
+++ b/src/java/com/threerings/presents/dobj/EntryAddedEvent.java
@@ -1,5 +1,5 @@
 //
-// $Id: EntryAddedEvent.java,v 1.10 2003/03/10 18:29:54 mdb Exp $
+// $Id: EntryAddedEvent.java,v 1.11 2003/07/20 17:02:26 mdb Exp $
 
 package com.threerings.presents.dobj;
 
@@ -67,7 +67,9 @@ public class EntryAddedEvent extends NamedEvent
     {
         if (!_alreadyApplied) {
             DSet set = (DSet)target.getAttribute(_name);
-            set.add(_entry);
+            if (!set.add(_entry)) {
+                Log.warning("Duplicate entryAdd: " + this);
+            }
         }
         return true;
     }