Index: server/listen.c
===================================================================
--- server/listen.c	(revision 1586508)
+++ server/listen.c	(working copy)
@@ -292,9 +292,22 @@
     }
 
     /* Initialize to our last configured ap_listener. */
-    last = ap_listeners;
-    while (last && last->next) {
-        last = last->next;
+    for (last = ap_listeners; last; last = last->next) {
+        apr_sockaddr_t *lsa = last->bind_addr;
+
+        if (lsa &&
+            port == lsa->port &&
+            ((!addr && !lsa->hostname) ||
+             ((addr && lsa->hostname) && !strcmp(lsa->hostname, addr)))) {
+            ap_log_perror(APLOG_MARK, APLOG_INFO, APR_SUCCESS, process->pool, APLOGNO(02619)
+                          "alloc_listener: ignoring duplicate Listen for %pI",
+                          sa);
+            return NULL;
+        }
+
+        if (!last->next) {
+            break;
+        }
     }
 
     while (sa) {