localize-test.php

<?php

// This is probably a bad idea.

class LocalizeTest {

	function __construct( $instance ) {
		$this->instance = $instance;
		add_action( 'wp_enqueue_scripts', array( $this, 'wp_enqueue_scripts' ) );
	}

	function wp_enqueue_scripts() {
		$instance_identifier = $this->instance;

		wp_enqueue_script( 'lorem', plugins_url('lorem.js',__FILE__) );
		wp_localize_script( 'lorem', 'lorem = (lorem ? lorem : new Object ); lorem.'.$instance_identifier, array(
			'this' => 'that'
		) );
	}
}

new LocalizeTest( 'one' );
new LocalizeTest( 'two' );

lorem.js

console.log( lorem );