diff --git a/application/AddressDB/AddressDBController.php b/application/AddressDB/AddressDBController.php
index 82bbacfa4..4223461dd 100644
--- a/application/AddressDB/AddressDBController.php
+++ b/application/AddressDB/AddressDBController.php
@@ -501,6 +501,20 @@ class AddressDBController extends mfBaseController {
               }
 
               if($address->rimo_id != $rimo_id || $address->visibility != $visibility) {
+
+                  if($address->rimo_id != $rimo_id) {
+                      // find if rimo id is in use already
+                      $test_rimo_id = ADBHausnummerModel::search(["rimo_id" => $rimo_id]);
+                      foreach($test_rimo_id as $test_address) {
+                          if($test_address && $test_address->id != $address->id) {
+                              $test_address->rimo_id = null;
+                              $test_address->save();
+                          }
+                      }
+
+
+                  }
+
                   $address->rimo_id = $rimo_id;
                   $address->visibility = $visibility;
                   $address->save();