From a66e8462d80edb04915f8f94770186728f3d5c04 Mon Sep 17 00:00:00 2001
From: Christian <cpw@weeksfamily.ca>
Date: Sat, 10 May 2014 14:53:08 -0400
Subject: [PATCH] Try and see if there is anything to the identityHashCode
 collision hypothesis. If you see this in your error messages, kindly let us
 know!

---
 .../fml/common/registry/FMLControlledNamespacedRegistry.java  | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/fml/src/main/java/cpw/mods/fml/common/registry/FMLControlledNamespacedRegistry.java b/fml/src/main/java/cpw/mods/fml/common/registry/FMLControlledNamespacedRegistry.java
index 9970e965b..a53d9250f 100644
--- a/fml/src/main/java/cpw/mods/fml/common/registry/FMLControlledNamespacedRegistry.java
+++ b/fml/src/main/java/cpw/mods/fml/common/registry/FMLControlledNamespacedRegistry.java
@@ -356,7 +356,9 @@ public class FMLControlledNamespacedRegistry<I> extends RegistryNamespaced {
         }
         if (getId(thing) >= 0) // duplicate object
         {
-            throw new IllegalArgumentException(String.format("The object %s has been registered twice, using the names %s and %s.", thing, getNameForObject(thing), name));
+            int foundId = getId(thing);
+            Object otherThing = getRaw(foundId);
+            throw new IllegalArgumentException(String.format("The object %s{%x} has been registered twice, using the names %s and %s. (Other object at this id is %s{%x})", thing, System.identityHashCode(thing), getNameForObject(thing), name, otherThing, System.identityHashCode(otherThing)));
         }
         if (GameData.isFrozen(this))
         {