diff --git a/mysql-test/suite/plugins/r/false_dupes-6543.result b/mysql-test/suite/plugins/r/false_dupes-6543.result
new file mode 100644
index 00000000000..22accaaae8a
--- /dev/null
+++ b/mysql-test/suite/plugins/r/false_dupes-6543.result
@@ -0,0 +1,5 @@
+install soname 'ha_federated';
+install soname 'ha_federated';
+install soname 'ha_federatedx';
+ERROR HY000: Function 'FEDERATED' already exists
+uninstall soname 'ha_federated';
diff --git a/mysql-test/suite/plugins/t/false_dupes-6543.test b/mysql-test/suite/plugins/t/false_dupes-6543.test
new file mode 100644
index 00000000000..ebdbe00e47c
--- /dev/null
+++ b/mysql-test/suite/plugins/t/false_dupes-6543.test
@@ -0,0 +1,18 @@
+#
+#    MDEV-6543 Crash if enable 'federatedx' when 'federated' plugin already enabled, and vice-versa
+#
+if(!$HA_FEDERATED_SO) {
+  skip Needs ha_federated.so;
+}
+if(!$HA_FEDERATEDX_SO) {
+  skip Needs ha_federatedx.so;
+}
+
+install soname 'ha_federated';
+# note: no error below! install soname ignores already loaded plugins
+install soname 'ha_federated';
+# note: an error here, even though plugin name is the same!
+--error ER_UDF_EXISTS
+install soname 'ha_federatedx';
+uninstall soname 'ha_federated';
+
diff --git a/sql/sql_plugin.cc b/sql/sql_plugin.cc
index c2ab07acd1a..d79cc0aaada 100644
--- a/sql/sql_plugin.cc
+++ b/sql/sql_plugin.cc
@@ -1040,7 +1040,7 @@ static st_plugin_int *plugin_insert_or_reuse(struct st_plugin_int *plugin)
 static bool plugin_add(MEM_ROOT *tmp_root,
                        const LEX_STRING *name, LEX_STRING *dl, int report)
 {
-  struct st_plugin_int tmp;
+  struct st_plugin_int tmp, *maybe_dupe;
   struct st_maria_plugin *plugin;
   uint oks= 0, errs= 0, dupes= 0;
   DBUG_ENTER("plugin_add");
@@ -1070,8 +1070,14 @@ static bool plugin_add(MEM_ROOT *tmp_root,
                                   (const uchar *)tmp.name.str, tmp.name.length))
       continue; // plugin name doesn't match
 
-    if (!name->str && plugin_find_internal(&tmp.name, MYSQL_ANY_PLUGIN))
+    if (!name->str &&
+        (maybe_dupe= plugin_find_internal(&tmp.name, MYSQL_ANY_PLUGIN)))
     {
+      if (plugin->name != maybe_dupe->plugin->name)
+      {
+        report_error(report, ER_UDF_EXISTS, plugin->name);
+        DBUG_RETURN(TRUE);
+      }
       dupes++;
       continue; // already installed
     }