Using onDuplicate() with insertMulti()

[palsypentertainment]

There is an old, closed thread regarding a similar issue, but it doesn't state if it was a user error or what.

I am having issues with using onDuplicate() with insertMulti()...... I'm getting a duplicate error at runtime.

Can someone confirm that onDuplicate() can be used with insertMulti()? Looking into the class, insertMulti() is just an insert() in a loop, right?

Here's my code of what I'm doing

$firstRow = reset($data);  
$updateColumns = array_keys($firstRow);  
$db->onDuplicate($updateColumns, $id);  
$result = $db->insertMulti($tablename, $data);

Am I'm doing it wrong?