diff -u -r1.3 -r1.4
--- NearestNeighbor.java	8 May 2009 18:56:36 -0000	1.3
+++ NearestNeighbor.java	25 Sep 2009 23:36:06 -0000	1.4
@@ -142,9 +142,14 @@

             IIdentifier id = raw_hit.getIdentifier();
             int channel_number = sid_helper.getElectrodeValue(id);
 

+            //  Check for duplicate RawTrackerHit
+            if (hit_to_channel.containsKey(raw_hit)) {
+                throw new RuntimeException("Duplicate hit: "+id.toString());
+            }
+

             //  Check for duplicate RawTrackerHits or channel numberss

-            if (hit_to_channel.containsKey(raw_hit) || channel_to_hit.containsKey(channel_number)) {
-                throw new RuntimeException("Duplicate hit or channel number");

+            if (channel_to_hit.containsKey(channel_number)) {
+                throw new RuntimeException("Duplicate channel number: "+channel_number);

             }
 
             //  Add this hit to the maps that relate channels and hits