Joining 2 uids in custom table with users table I have a custom table. Inside that table I have 2 uids.

Using hook_views_data_alter I know how to make a join with users table. My field is called also "uid".

The join looks like this:

    $data['ofertas_producto']['table']['join'] = array(
        'users' =&gt; array(
            'left_field' =&gt; 'uid',
            'field' =&gt; 'uid',
        ),
    );

    $data['ofertas_producto']['uid']['relationship'] = array(
        'base' =&gt; 'users',
        'field' =&gt; 'uid',
        'handler' =&gt; 'views_handler_relationship',
        'label' =&gt; 'Creador del Producto',
    );


As you can see the join defined in the first array has only one possible definition with the users table and one left field inside of it. So if I want to define another join with a second field "uid_2" it will override the first declared join.

Am I right? Thanks for your knowledge.
It will not be overridden. It will be another relationship. See the example at the API docs: https://api.drupal.org/api/views/views.api.php/function/hook_views_data_alter/7

See also the example here: https://stackoverflow.com/a/11103419/2467536