D7: form input name array
You need to specify them like this and set #tree to TRUE. Like this.

$form['MyArray']['#tree'] = TRUE;
$form["MyArray"][1] = _d7_taxonomy_term_select($node_type-&gt;name, 2, $default_value);
$form["MyArray"][2] = _d7_taxonomy_term_select($node_type-&gt;name, 2, $default_value);
$form["MyArray"][3] = _d7_taxonomy_term_select($node_type-&gt;name, 2, $default_value);