diff --git a/course/moodleform_mod.php b/course/moodleform_mod.php
index fc1c5ab2b95..9bafe21e2fc 100644
--- a/course/moodleform_mod.php
+++ b/course/moodleform_mod.php
@@ -358,6 +358,21 @@ abstract class moodleform_mod extends moodleform {
             }
         }
 
+        // Conditions: Verify that the user profile field has not been declared more than one
+        if (array_key_exists('conditionfieldgroup', $data)) {
+            // Array to store the existing fields
+            $arrcurrentfields = array();
+            // Error message displayed if any condition is declared more than once
+            $stralreadydeclaredwarning = get_string('fielddeclaredmultipletimes', 'condition');
+            foreach ($data['conditionfieldgroup'] as $i => $fielddata) {
+                if (in_array($fielddata['conditionfield'], $arrcurrentfields)) {
+                    $errors["conditionfieldgroup[{$i}]"] = $stralreadydeclaredwarning;
+                }
+                // Add the field to the array
+                $arrcurrentfields[] = $fielddata['conditionfield'];
+            }
+        }
+
         return $errors;
     }
 
diff --git a/lang/en/condition.php b/lang/en/condition.php
index ebce0df087d..2eab10ad5f9 100644
--- a/lang/en/condition.php
+++ b/lang/en/condition.php
@@ -48,6 +48,7 @@ $string['completion_incomplete'] = 'must not be marked complete';
 $string['completion_pass'] = 'must be complete with pass grade';
 $string['configenableavailability'] = 'When enabled, this lets you set conditions (based on date, grade, or completion) that control whether an activity or resource can be accessed.';
 $string['enableavailability'] = 'Enable conditional access';
+$string['fielddeclaredmultipletimes'] = 'You can not declare the same field more than once per activity.';
 $string['grade_atleast'] = 'must be at least';
 $string['gradecondition'] = 'Grade condition';
 $string['gradecondition_help'] = 'This setting determines any grade conditions which must be met in order to access the activity.