Multiple Google Analytics in Better AMP WordPress Plugin, Use it as plugin or paste it in your function file.

multiple-analytics-better-amp.php

<?php 
/*
Plugin Name: Better AMP Mod : Multiple Analytics Code 
Plugin URI: https://www.whoisabhi.com/
Description: Update your Analytics Code in this file below. Replicate Triggers if you need multiple Trackers.
Author: Abhishek
Version: 1.0
Author URI: https://www.whoisabhi.com/
*/

// Enqueue AMP Analytics js in header
function peenak_amp_js(){
	better_amp_enqueue_script( 'amp-analytics', 'https://cdn.ampproject.org/v0/amp-analytics-0.1.js' );
}
add_action( 'better-amp/template/enqueue-scripts', 'peenak_amp_js', 100 );

// Add analytics Code
function peenak_add_multiple_analytics(){
	?>
		<amp-analytics type="googleanalytics">
			<script type="application/json">
				{
	"triggers": {
		"trackPageview": {
			"on": "visible",
			"request": "pageview",
			"vars": {
				"account": "UA-XXXXXX-1"
			}
		},
		"trackPageview2": {
			"on": "visible",
			"request": "pageview",
			"vars": {
				"account": "UA-XXXXXX-2"
			}
		}
	}
}
		    	</script>
		</amp-analytics>
	<?php
}
add_action("better-amp/template/footer","peenak_add_multiple_analytics");