diff --git a/app/plugins/OrcidSource/config/plugin.json b/app/plugins/OrcidSource/config/plugin.json
index f7e625558..e3113e8b1 100644
--- a/app/plugins/OrcidSource/config/plugin.json
+++ b/app/plugins/OrcidSource/config/plugin.json
@@ -49,8 +49,7 @@
         },
         "indexes": {
           "orcid_source_tokens_i1": {
-            "columns": [ "orcid_source_id",  "orcid_identifier"],
-            "unique": true
+            "columns": [ "orcid_source_id",  "orcid_identifier"]
           },
           "orcid_source_tokens_i2": { "columns": [ "orcid_identifier" ] },
           "orcid_source_tokens_i3": { "needed": false, "columns": [ "orcid_source_id" ] }
diff --git a/app/plugins/OrcidSource/resources/locales/en_US/orcid_source.po b/app/plugins/OrcidSource/resources/locales/en_US/orcid_source.po
index a670369b1..b8cf16f62 100644
--- a/app/plugins/OrcidSource/resources/locales/en_US/orcid_source.po
+++ b/app/plugins/OrcidSource/resources/locales/en_US/orcid_source.po
@@ -58,6 +58,9 @@ msgstr "{0} was not found"
 msgid "error.response.no_orcid"
 msgstr "ORCID identifier missing from response."
 
+msgid "error.exists"
+msgstr "Orcid Token already exists with this Identifier"
+
 msgid "field.OrcidSources.api_type"
 msgstr "API Type"
 
diff --git a/app/plugins/OrcidSource/src/Model/Table/OrcidTokensTable.php b/app/plugins/OrcidSource/src/Model/Table/OrcidTokensTable.php
index 9a2519a1c..6db305dc1 100644
--- a/app/plugins/OrcidSource/src/Model/Table/OrcidTokensTable.php
+++ b/app/plugins/OrcidSource/src/Model/Table/OrcidTokensTable.php
@@ -29,6 +29,7 @@
 
 namespace OrcidSource\Model\Table;
 
+use Cake\ORM\RulesChecker;
 use Cake\ORM\Table;
 use Cake\Utility\Security;
 use Cake\Validation\Validator;
@@ -119,6 +120,24 @@ public function beforeMarshal(EventInterface $event, \ArrayObject $data, \ArrayO
 
     }
 
+  /**
+   * Define business rules.
+   *
+   * @since  COmanage Registry v5.2.0
+   * @param  RulesChecker $rules RulesChecker object
+   * @return RulesChecker
+   */
+
+  public function buildRules(RulesChecker $rules): RulesChecker {
+    $rules->add(
+     $rules->isUnique(
+         ["orcid_source_id",  "orcid_identifier"]),
+        __d('orcid_source', 'error.exists')
+    );
+
+    return $rules;
+  }
+
     /**
      * Unencrypt a value previously encrypted using salt
      *