CI 3.1.0 multi delete and update, is a bug?

In a method I have two queries, the first performs a delete on two tables and everything works well.
After I have a second query to update another table in this way:

PHP Code:

// Delete
$this->db->where('id_pdv', (int)$id)->delete( ['table_1', 'tabel_2'] );

// Update
$this->db->where('id', (int)$id)->update('pdv', $array_update); 


The update query fails because it inherits the where clause of the delete query like this:

…WHERE id_pdv = 123 AND id = 123

This only happens if the delete query receives multiple tables.


To get the expected result is necessary:

1) Run two separate delete

or

2) Use the delete this way:

PHP Code:

$this->db->delete( ['table_1','table_2'], ['id_pdv' => (int)$id] ); 


or

3) Perform

PHP Code:

$this->db->reset_query(); 


before the update


I'm wrong, or is it a bug?

Thanks