Index: src/main/java/org/apache/jackrabbit/core/jmx/JmxRegistryImpl.java
===================================================================
--- src/main/java/org/apache/jackrabbit/core/jmx/JmxRegistryImpl.java	(revision 1089811)
+++ src/main/java/org/apache/jackrabbit/core/jmx/JmxRegistryImpl.java	(working copy)
@@ -76,7 +76,9 @@
 
         for (ObjectName o : registry) {
             try {
-                server.unregisterMBean(o);
+                if(server.isRegistered(o)){
+                    server.unregisterMBean(o);    
+                }
             } catch (Exception e) {
                 e.printStackTrace();
             }
@@ -94,7 +96,12 @@
      */
     public void register(JackrabbitBaseMBean bean, ObjectName name)
             throws Exception {
-        this.server.registerMBean(bean, name);
+        if (this.registry.contains(name)) {
+            return;
+        }
+        if (!this.server.isRegistered(name)) {
+            this.server.registerMBean(bean, name);
+        }
         this.registry.add(name);
     }