diff --git a/YiiConditionalValidator.php b/YiiConditionalValidator.php
index 3d3c0fd..6c4648f 100644
--- a/YiiConditionalValidator.php
+++ b/YiiConditionalValidator.php
@@ -178,7 +178,8 @@ protected function runValidators(array $validatorsData, $discardErrorsAfterCheck
                 $object->clearErrors();
 
                 if (!$discardErrorsAfterCheck) {
-                    $object->addErrors($newErrors);
+                    // Merge new with 'existing' errors to prevent the last error within the same group (if/then) overwrite all others
+                    $object->addErrors(CMap::mergeArray($errorsBackup, $newErrors));
                 }
 
                 if ($returnFalseOnError) {