The currency determines which buttons are eligible, so an SDK load is only usable with 1 currency at a time.

To support multiple currencies, you must reload the SDK on the page and re-render any buttons afterward (and createOrder, when called, must specify amounts in the single currency that matches).

A new alternative you can try is to load the SDK multiple times on the page using the data-namespace parameter, to specify a name other than the default paypal.

An example....

<h3>USD buttons...</h3>
<div id="paypal-button-container-1" />

<script src="https://www.paypal.com/sdk/js?client-id=test&currency=USD" data-namespace="paypalUSD"></script>
<script>
    paypalUSD.Buttons({
        //...
    }).render('#paypal-button-container-1');
</script>


<hr />


<h3>AUD buttons...</h3>
<div id="paypal-button-container-2" />

<script src="https://www.paypal.com/sdk/js?client-id=test&currency=AUD" data-namespace="paypalAUD"></script>
<script>
    paypalAUD.Buttons({
        //...
    }).render('#paypal-button-container-2');
</script>

</script>

In general, unless you have a specific business need to receive multiple currencies in your account, it's simpler to just use an international currency like USD or EUR and let PayPal show the conversion at payment time if the buyer is going to use a funding source in a differrent currency like GBP, NZD, etc