Index: trunk/src/org/openstreetmap/josm/data/osm/User.java
===================================================================
--- trunk/src/org/openstreetmap/josm/data/osm/User.java	(revision 2454)
+++ trunk/src/org/openstreetmap/josm/data/osm/User.java	(revision 2455)
@@ -1,4 +1,6 @@
 // License: GPL. Copyright 2007 by Immanuel Scholz and others
 package org.openstreetmap.josm.data.osm;
+
+import static org.openstreetmap.josm.tools.I18n.tr;
 
 import java.util.ArrayList;
@@ -48,6 +50,11 @@
      */
     public static User  createOsmUser(long uid, String name) {
-        User user = new User(uid, name);
-        userMap.put(user.getId(), user);
+        User user = userMap.get(uid);
+        if (user == null) {
+            user = new User(uid, name);
+            userMap.put(user.getId(), user);
+        }
+        if (!user.getName().equals(name))
+            throw new DataIntegrityProblemException(tr("User with the same uid but different name found"));
         return user;
     }