diff -up net-snmp-5.4.1/agent/mibgroup/agent/extend.c.backup_patch_14 net-snmp-5.4.1/agent/mibgroup/agent/extend.c
--- net-snmp-5.4.1/agent/mibgroup/agent/extend.c.backup_patch_14	2007-07-06 17:32:59.000000000 +0200
+++ net-snmp-5.4.1/agent/mibgroup/agent/extend.c	2008-07-25 12:53:44.000000000 +0200
@@ -450,6 +450,9 @@ extend_parse_config(const char *token, c
         extension->command  = strdup( exec_command );
         if (cptr)
             extension->args = strdup( cptr );
+    } else {
+    	snmp_log(LOG_ERR, "Duplicate MIBOID '%s' detected in exec statement, only the first one will be used.\n", exec_name);
+    	return;
     }
 
 #ifndef USING_UCD_SNMP_EXTENSIBLE_MODULE