WordPress Custom Menu Widget ==> change to 2-column

I am trying to create a Custom Menu Widget that has two columns (i.e., wherein I can select two different menus and have them display side-by-side within a single sidebar widget).

I found a tutorial on how to create a two column text widget, however I cannot figure out how to edit the Custom Menu widget functions to add and implement an additional menu — my attempts to create an additional menu variable (i.e., “$menus1” and “$menus2” below) break WordPress (“unexpected T string” error).

Does the “$instance” array have a pre-defined key called ‘nav_menu’ or are this key and its value created by the “form” function? If the latter, can I define ‘nav_menu1’ and ‘nav_menu2’ keys (I tried this before but also got the “unexpected T string” error)?

<?php
/**
 * Custom Menu widget copied from default WP Widget Class and adjusted for 2-columns
 */

class SO_ABC_Tag_List_Widget_2col extends WP_Widget {

    function __construct() {
        $widget_ops = array( 'description' => __('By adding this widget you can select your alphabetical tags menu to display on your website.') );
        parent::__construct( 'so_abc_tags_2col', __('SO ABC Tag List 2 col'), $widget_ops );
    }

    function widget($args, $instance) {
        // Get menu
        $nav_menu1 = ! empty( $instance['nav_menu'] ) ? wp_get_nav_menu_object( $instance['nav_menu'] ) : false;
        $nav_menu2 = ! empty( $instance['nav_menu'] ) ? wp_get_nav_menu_object( $instance['nav_menu'] ) : false;

        if ( !$nav_menu )
            return;

        $instance['title'] = apply_filters( 'widget_title', empty( $instance['title'] ) ? '' : $instance['title'], $instance, $this->id_base );

        echo $args['before_widget'];

        if ( !empty($instance['title']) )
            echo $args['before_title'] . '<i class="icon-tags"></i> ' . $instance['title'] . $args['after_title'];

<div style="float: left; width: 45%">
        wp_nav_menu( array( 'fallback_cb' => '', 'menu' => $nav_menu1 ) );
</div> 

<div style="float: left; width: 45%"></div>     
        wp_nav_menu( array( 'fallback_cb' => '', 'menu' => $nav_menu2 ) );
</div>
        echo $args['after_widget'];
    }

    function update( $new_instance, $old_instance ) {
        $instance['title'] = strip_tags( stripslashes($new_instance['title']) );
        $instance['nav_menu'] = (int) $new_instance['nav_menu'];
        $instance['nav_menu'] = (int) $new_instance['nav_menu'];
        return $instance;
    }

    function form( $instance ) {
        $title = isset( $instance['title'] ) ? $instance['title'] : '';
        $nav_menu1 = isset( $instance['nav_menu'] ) ? $instance['nav_menu'] : '';
        $nav_menu2 = isset( $instance['nav_menu'] ) ? $instance['nav_menu'] : '';

        // Get menus
        $menus1 = get_terms( 'nav_menu', array( 'hide_empty' => false ) );
        $menus1 = get_terms( 'nav_menu', array( 'hide_empty' => false ) );

        // If no menus exists, direct the user to go and create some.
        if (( !$menus1  ) AND ( !menus2 )) {
            echo '<p>'. sprintf( __('No menus have been created yet. <a href="%s">Create some</a>.'), admin_url('nav-menus.php') ) .'</p>';
            return;
        }
        ?>
        <p>
            <label for="<?php echo $this->get_field_id('title'); ?>"><?php _e('Title:') ?></label>
            <input type="text" class="widefat" id="<?php echo $this->get_field_id('title'); ?>" name="<?php echo $this->get_field_name('title'); ?>" value="<?php echo $title; ?>" />
        </p>
        <p>
            <label for="<?php echo $this->get_field_id('nav_menu'); ?>"><?php _e('Select Menu:'); ?></label>
            <select id="<?php echo $this->get_field_id('nav_menu'); ?>" name="<?php echo $this->get_field_name('nav_menu'); ?>">
        <?php
            foreach ( $menus1 as $menu1 ) {
                echo '<option value="' . $menu1->term_id . '"'
                    . selected( $nav_menu, $menu1->term_id, false )
                    . '>'. $menu1->name . '</option>';
            }
        ?>
            </select>
        </p>
        <p>
            <label for="<?php echo $this->get_field_id('nav_menu'); ?>"><?php _e('Select Menu:'); ?></label>
            <select id="<?php echo $this->get_field_id('nav_menu'); ?>" name="<?php echo $this->get_field_name('nav_menu'); ?>">
        <?php
            foreach ( $menus2 as $menu2 ) {
                echo '<option value="' . $menu2->term_id . '"'
                    . selected( $nav_menu, $menu2->term_id, false )
                    . '>'. $menu2->name . '</option>';
            }
        ?>
            </select>
        </p>
        <?php
    }
}